ABSTRACT— Eighty-eight consecutive hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) positive, heterosexual patients of Caucasian origin presenting with chronic hepatitis were followed for 1 to 15 years (mean, 5.4 years). During the study period, 45 (51%) patients cleared HBeAg and hepatitis B virus-deoxyribonucleic acid from serum and were followed for 53 ± 29 months (mean ± SD) after seroconversion to antibody to hepatitis B e antigen. All patients manifested biochemical improvement. During follow-up, 10 (22%) of the 45 patients experienced spontaneous reactivation of hepatitis B replication with reappearance of serum hepatitis B virus-deoxyribonucleic acid and, in 4 patients, of hepatitis B e antigen. All patients then showed biochemical exacerbation of disease. These serologic events were transient, lasting an average of 12 months, in 8 (80%) patients. All patients were asymptomatic or minimally symptomatic. Histologic findings of liver tissue from 7 patients showed progression from chronic active hepatitis to active cirrhosis in 2 (28%) patients, while in the remaining 6 cases histology remained unchanged or improved from chronic active to chronic persistent hepatitis. These data indicate that spontaneous reactivation of hepatitis B infection occurs in heterosexual patients with chronic hepatitis B and this event is usually transient and asymptomatic, although in some patients it may be the major cause of progressive hepatic damage.