Dr. Guillermo Marrero is an internist practicing in Oviedo, FL. Dr. Marrero specializes in the medical treatment of adults. Internists can act as a primary physician or a consultant to a primary physician. They manage both common and rare diseases. Dr. Marrero provides comprehensive care and manages treatment with surgeons as well. Internists establish long-term relationships with their patients and incorporate disease prevention and mental health care into their practice.