An estimated 350 million persons worldwide are chronically infected with hepatitis B virus (HBV). Immunosuppression after renal transplantation seems to enhance viral replication and increase the risk of developing cirrhosis and hepatocellular carcinoma. This retrospective study was performed to assess the prevalence among and serological status of HBV infection after renal transplantation at a single university Brazilian center. Thirty six (4.2%) patients among 850 kidney recipients showed positive HBsAg for more than 6 months; 31 were hepatitis B surface antigen (HBsAg) positive at transplantation. Of the 15 hepatitis B e antigen (HbeAg) positive patients, six had spontaneous HBeAg seroconversion and three also had HBsAg clearance. An additional two showed HBeAg clearance with Lamivudine without seroconversion. Among 15 HBeAg-negative patients, three developed HBeAg reversion with no elevation of alanine transferase (ALT) levels and one had HBsAg clearance. Only one patient had acute exacerbation of hepatitis B (ALT > 20 times normal range) but remained HbeAg negative. During follow-up, five patients became HBsAg positive; two reactivations of resolved hepatitis B, two with previous anti-HBS induced by vaccination, and one with no serological marker for HBV. Lamivudine was prescribed for 16 patients, two of whom had HbeAg clearance without seroconversion and five who developed viral resistance to Lamivudine after a mean of 29.2 months. No hepatocellular carcinoma or deaths related to hepatitis B were seen in this group. In summary, prevalence of HBV in kidney transplant patients was 4.2%. Immunosuppression after renal transplantation in HBV infection led to an increased risk of liver complications and changes in HBV serological status.