BACKGROUND: Chronic Hepatitis B (CHB) remains a major cause of morbidity in several parts of the world. Aircrew with immune-active hepatitis are unfit for flying duties due to the risk of acute hepatic decompensation; those who have begun on treatment are generally also disqualified from flying duties due to the potential side effects of antiviral treatment. As treatment endpoints for nucleos(t)ide analogues (NUC) are typically achieved after prolonged therapy, aircrew treated for CHB may be subjected to an extended period of flying restriction.METHODS: We present a retrospective case series of seven aircrew who were returned to flying duties while on varying combinations of NUC for the treatment of CHB. All seven aircrew were comanaged by the flight surgeon and hepatologist, reviewed by a panel of flight surgeons, and had achieved normalized liver function tests prior to resumption of flying duties; two out of the seven aircrew had detectable serum Hepatitis B virus (HBV) DNA when reinstated back to flying duties. Only one aircrew member experienced side effects from the NUC treatment. This was promptly evaluated and managed prior to resumption of flying duties to ensure flight safety.DISCUSSION: Aircrew with CHB infection can be safely allowed back to flying duties, especially when their conditions have been well controlled via treatment with any of the NUC regimes. While there are limited studies evaluating the use of NUC in aircrew performing flight duties, our study has shown that NUC are generally well tolerated and have a good safety profile which is compatible with flying duties.Tan D, Kwan C, Tan BBC, Gan WH. Returning aircrew with chronic Hepatitis B back to flying while on nucleos(t)ide analogues. Aerosp Med Hum Perform. 2019; 90(1):37-42.