Vacuoles, aqueous fissures, crumb-like opacities, color iridescence, and thickening under the posterior capsule in the lens were found in 86% of 45 patients with chronic active hepatitis B, mean age 33 +/- 2.5 years. Seven percent of patients developed posterior capsule cataracts. examinations of 42 patients with cirrhosis of the liver caused by hepatitis B virus (mean age 39 +/- 2 years) revealed changes in the lens in 100% and mature cataracts in 36% of the eyes. In 2 of the 4 healthy HBsAg carriers aged 31 to 35 initial changes in the lens and accumulation of antilenticular antibodies in the lacrimal fluid and serum. A reliable difference by all the tested parameters between the examinees and controls (HBsAg-negative age-matched blood donors, n = 20) confirms a relationship between hepatitis B infection and lenticular abnormalities in subjects of a productive age. Markers of hepatitis B virus (HBsAg, HBeAg, anti-HBs, anti-HBe, anti-HBc) were found in the lenticular mass and blood sera of 11 out of 14 children aged 1.5 to 4 operated on for congenital nonhereditary cataracts; in 4 of them viral replication still continued. HBV markers of chronic viral carriership or markers of potential contagiousness were found in the sera of their mothers (in 6 and 5 sera, respectively), this indicating a possible intrauterine infection of children. The findings evidence a possible etiological role of hepatitis B virus infection in the formation of congenital and early acquired cataracts.