Prof. Sulkowski has been the principal investigator for more than 120 clinical trials related to the management of viral hepatitis B and C in persons with and without HIV co-infection. He was the global principal investigator for more than a dozen trials, including the largest clinical trial of agents for the treatment of hepatitis C (New England Journal of Medicine, 2009) and the vanguard study of combination therapy with direct inhibitors of the HCV NS5A and NS5B non-structural proteins (New England Journal of Medicine, 2014). He is the past-chair of the Hepatitis Transformative Sciences Group of the National Institute of Health-funded adult AIDS Clinical Trials Group (ACTG) where he led translational studies of liver disease, namely hepatitis B and C virus. He is an elected member of the American Society for Clinical Investigation (2011) and the American Association of Physicians (2017).