United Gastroenterologists is a Southern California gastroenterology practice that grew from a small independent medical group founded by Dr. Thomas Eastman and Dr. John Hong. Established as United Gastroenterologists in 2002, the practice expanded its regional care network and developed services including ambulatory surgery centers, diagnostic imaging, medical weight loss, pathology, and clinical research. In 2017, it expanded into United Medical Doctors, a broader independent, multispecialty practice serving communities across Southern California.

The organization offers medical and surgical care through a large network of providers and locations. Its specialties include gastroenterology, hepatology, colorectal surgery, and pediatric gastroenterology, alongside services such as imaging, infusion therapy, and weight-loss care. Patients can arrange office consultations, follow-up visits, and telemedicine appointments, with online scheduling available for many providers. The practice accepts most major PPO plans, Medicare, Tricare, and some HMO plans; patients are advised to confirm coverage with their preferred office. United Gastroenterologists emphasizes compassionate care, prevention, diagnosis, and treatment, aiming to build trusting relationships with patients while supporting their overall well-being.