Hepatitis B infection is a major public health problem. Approximately two billion people worldwide have been infected with hepatitis B virus (HBV) during their lifetime. In some patients Hepatitis B may get converted into a dormant stage and get reactivated during immunosupression like chemotherapy. Hepatitis B complicates management of cancers as reactivation of hepatitis B not only increases morbidity and mortality but also prolongs chemotherapy and may result in inadequate outcomes. Several approaches have been developed to prevent reactivation of hepatitis B in cancer patients. One such approach is active immunization of all cancer patients. The present study has been done to understand the problem of hepatitis B in cancer patients and to evaluate the efficacy of vaccination in prevention of hepatitis B in cancer patients.