Diagnostics are the hidden engine of precision medicine, yet too often overlooked. Scientist-entrepreneur José Pereira Leal takes readers inside the world of diagnostics innovation, where the most important advances in healthcare begin not with drugs or devices, but with the ability to measure, predict, and guide treatment decisions. From founding Ophiomics, a company pioneering AI-powered liver disease diagnostics, to navigating regulatory frameworks and investor skepticism, Pereira Leal reveals the challenges and breakthroughs of building a precision diagnostics company from the ground up. Along the way, he makes a compelling case: without smarter diagnostics, the promise of precision medicine will fail the millions of patients who most need it. Equal parts memoir, manifesto, and field guide, this book offers scientists, clinicians, innovators, policymakers, and investors a unique insider’s perspective on why diagnostics are the true foundation of personalized healthcare, how AI and genomics are revolutionizing medical decision-making, and the hard-won lessons from building a diagnostics company in today’s complex regulatory landscape. Precision Diagnostics is both urgent call to action and practical roadmap: for investors seeking healthcare’s next breakthrough, innovators building tomorrow’s medical tools, and leaders determined to make precision medicine accessible to everyone, not just the privileged few.