Dr Gish is currently the Medical Director of both the Hepatitis B Foundation in Doylestown, PA, and the American Pacific Health Foundation in San Diego, CA.  He is an Adjunct Professor of Medicine at the University of Nevada Schools of Medicine in Las Vegas and Reno, as well as an Adjunct Professor of Pharmacy at the University of California, San Diego, and a Clinical Professor of Medicine at Loma Linda University.  

He received his medical degree from the University of Kansas; Dr Gish then went on to complete his residency at the University of California, San Diego, and his fellowship in gastroenterology and hepatology, which included transplant medicine, at the University of California, Los Angeles.

Dr Gish has an active research program in viral hepatitis, MASLD, MAFLD, and autoimmune liver disease. He was a major contributor to identifying methods of detection for hepatitis B and C, as well as studies that led to the genotypic classification of these viruses and methods now in use worldwide. He has a special interest in public policy related to liver cancer and liver transplantation; Dr Gish also developed an outreach program that is now a leading liver transplant center in California and Nevada. 

He is involved in patient care and patient advocacy groups, both in the US and in an international setting, focusing on equitable access and public health policy for liver health. In addition, Dr Gish is a fellow of the AASLD, AST, and ACP, as well as a member of numerous professional societies including EASLD, APASL, ASTP, and ALF.

He has published more than 700 original articles, review articles, abstracts, and book chapters and has served on editorial boards of the American JournaI of Gastroenterology, Journal of Hepatology, Digestive Diseases and Sciences, and Gastroenterology, among many others.