The prevalence of delta infection among urban Egyptians is reported for the first time. Sera of 44 HBsAg-positive chronic liver disease (CLD) patients and 48 asymptomatic HBsAg carriers were screened for antibodies to hepatitis delta antigen (anti-HD). Anti-HD was found in 21 (47.7%) of the patients compared with 4 (8.3%) of the asymptomatic carriers. The difference was statistically significant at the 0.001 level. Anti-HD was present in 14 out of 24 (58.3%) subjects with histological diagnosis of chronic active hepatitis, 4 of 9 (44.9%) with cirrhosis, and 3 out of 11 (27.2%) with chronic persistent hepatitis. This study points to a high prevalence of hepatitis delta virus in Egypt.