Few data on chronic hepatitis B (CHB) have been published in our country, despite the fact that it is responsible for more than 50% of all types of chronic hepatitis. From 1968 to 1988, 164 patients were attended with the diagnosis of CHB, from whom 136 (82.9%) were male. Only 11 (8.1%) admitted homosexual behavior. Twenty six out of 39 (66.7%) health professionals were medical doctors; among them 12 (46.2%) were surgeons. The mode of transmission was unknown in 55% of the cases, but vertical and sexual transmissions were also frequent. Commercial gammaglobulin, used with prophylactic purpose, was probably responsible for eight cases between 1972 and 1975. The most frequent forms of CH were chronic active hepatitis (CAH) and liver cirrhosis (LC): 72 or 43.9% and 53 or 32.3%, respectively. The predominance of HBeAg (66.4%) was observed in all forms of CHB. Repeated biopsies showed that chronic lobular hepatitis (CLH) and chronic persistent hepatitis (CPH) may occasionally progress to CAH. This form may persist as such for some years or progress to cirrhosis. In a few cases the evolution to CPH was observed. In the long term follow-up of our patients, the appearance of hepatocellular carcinoma was observed in 8 (4.9%).