In this review article, we hypothesize that Hepatitis B Virus Vaccine (HBV-V) and certain antigens of Hepatitis B Virus (HBV) could act as anticancer immunoadjuvants in addition to their role of preventing HBV-associated liver cancer. Evidence suggests that in animal breast cancer and melanoma models, combining hepatitis B-surface antigen (HBsAg) with other cancer antigens resulted in enhanced antitumour activity. HBsAg shares antigenic mimicry with healthy and malignant cells including squamous epithelia, thymic epithelia, bladder- and colon cancer cells. There exist anecdotal reports and small case series about spontaneous remission of leukaemias and neuroblastoma following acute HBV-infection. Recent studies also exist showing HBV-carrier state is a good prognostic factor for intrahepatic cholangiocarcinoma. Further epidemiological studies and animal experiments are necessary whether HBV-Vs exert additional immunoadjuvant benefits besides lowering the risk of liver cancer.