By YiDing Yu, MD, a practicing physician and serial health tech and AI entrepreneur

The other day, I took a call from a former colleague. A primary care internist, he splits his time seeing patients and leading innovative projects at a large academic medical center. But recently, he’s begun contemplating a move outside of traditional medicine. Over the years, he’s received a few inbound inquiries from health care start-ups, and he wanted to talk through what a Chief Medical Officer (CMO) role at a start-up actually entails.

This is one of the most common questions I get from aspiring physician tech leaders. Before I was ever a CEO or general manager, I was a CMO. It’s a role that can be incredibly rewarding, yet diverse and challenging.

Let’s start with the real talk: if you’ve seen one CMO job, you’ve seen one CMO job. You’ll hear this from recruiters, and it’s borne out in my real-life experience. The role varies wildly depending on the stage of the company and the sector of health care. At early-stage companies, I expect CMOs to wear every hat that possibly relates to their doctor training. I have been a one-person evangelist, medical director, ethics committee, compliance expert, product consultant, QA tester… the list continues. You may not be the expert in each of these areas, but you should expect to be the point person to hold accountability until you can find the right advisor, consultant, or team to take over the job.

As companies mature, the role of a CMO becomes more predictable but still a chameleon that transforms by health care sector. Are we talking biotech, health tech, or a tech-enabled service? Each demands a different focus and skillset from its CMO.

The Many Faces of a Startup CMO

In a biotech startup, the CMO lives and breathes medical affairs. Your focus may include clinical strategy, trial design, regulatory submissions, and engaging with key opinion leaders in the therapeutic area. You’re the bridge between the science (and the Chief Scientific Officer) and its eventual application in patients. This means a deep understanding of the drug or device approval process, adherence to national and international regulatory requirements, and exercising vigilance over responsible marketing and education. As CMO, you need the ability to navigate complex regulatory landscapes and communicate effectively with both scientific and business stakeholders.

Shift gears to a health tech startup, and the CMO role morphs significantly. CMOs at health tech companies help define and articulate the product vision and the user experience. You are a master communicator. Externally, you’re an evangelist for the company, speaking at conferences and joining sales calls to turn skeptics into believers. Internally, you’re a product and customer evangelist, working across product, engineering, and customer teams to bring the voice of the clinician and patient into every design decision. Frequently the lone clinician at earlier-stage companies, you are also the go-to person for clinical, regulatory, and general “how health care works” questions, transforming tools like AI and automation into meaningful applications. I’ve even seen CMO job descriptions that include running customer advisory boards, ethics, and clinical research partnerships.

Finally, in a tech-enabled services startup, the CMO role is closest to what we might expect of a traditional CMO. Imagine a virtual care platform, a chronic disease management service, or a value-based care model. At these companies, CMOs are often responsible for clinical quality, patient safety, guideline adherence, and direct oversight of the clinical workforce. You’ll be setting clinical protocols, designing care pathways, and ensuring consistent, high-quality care at scale. You might be involved in credentialing, peer review, and developing new service lines. Your understanding of health care operations, quality metrics, and the nuances of provider-patient interactions in novel delivery models is crucial. The most successful CMOs in such roles are innovative and nimble: they can build, adapt, and deploy care models faster than any traditional health care system.

A Universal Evangelist

Despite these differences, there’s one consistent theme that permeates every CMO role: you are an external evangelist. Whether you’re talking to investors, potential customers, regulatory bodies, or even future hires, you are the credible medical voice of the company. You embody clinical integrity and gravitas, and you leave a lasting impression for the game-changing impact of your product or service.

How much time you spend wearing the evangelist hat can vary. In an early-stage startup, you might be spending 50−70% of your time on “sales” activities — pitching, presenting, and networking to drive sales, adoption, and partnerships. As the company grows and develops a scalable, winning sales pitch, the evangelist role will change to more customer adoption and thought leadership activities, but evangelism remains an integral part of the role.

For some physicians, being a ‘salesperson’ feels unnatural or even uncomfortable. Personally, when I truly believe in the product or service I’m delivering, I feel energized and excited to explain why it is so meaningful. Evangelism feels natural when you believe. That said, if the idea of constantly communicating your company’s value proposition and clinical rationale doesn’t excite you, then the honest reality is that the CMO role might not be the best fit.

Fortunately, there are other incredible opportunities for physicians in startups, and I’ve written about these previously [link last article]. A medical director, for instance, would be more focused on internal clinical oversight, guideline development, or clinical operations, with less emphasis on external-facing responsibilities. And a clinical product leader translates clinical needs into product requirements, guiding product development from within. Both of these roles offer their own exciting growth trajectories and can be immensely fulfilling.

But if that evangelist role does resonate with you, then being a startup CMO can be one of the most fun and rewarding roles imaginable. You truly get to be a jack-of-all-trades. One moment, you’re diving deep into clinical literature; the next, you’re strategizing with the sales team or brainstorming with engineers.

If you are ready to take on a CMO role, I have one final secret: for the right candidate, the CMO role is tailored to you. Because the role is so varied and great CMOs are in short supply, I’ve found that most companies are open to adapting the role for the right person. For example, if you’re an experienced researcher and you believe clinical research partnerships will take a tech company to the next level, then absolutely advocate to add that to your mandate. Craft the role into the ideal role for you and the company.

You’ll be surprised how often the answer is yes.