By the baby experts at Mayo Clinic. Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. Doctors from every medical specialty work together to care for patients, joined by common systems and a philosophy that the needs of the patient come first. Over 3,600 physicians and scientists and 50,000 allied staff work at Mayo, which has sites in Rochester, Minn.; Jacksonville, Fla.; and Scottsdale/Phoenix, Ariz. Collectively, Mayo Clinic treats more than 500,000 patients a year. For more than 100 years, millions of people from all walks of life have found answers at Mayo Clinic. Mayo Clinic works with many insurance companies, does not require a physician referral in most cases and is an in-network provider for millions of people.