The overall prevalence of delta-antibody among 80 patients with chronic infection of hepatitis B virus in the Los Angeles area was found to be 24%. Twenty-three patients had a histologic diagnosis of persistent hepatitis and 57 had chronic active hepatitis with or without cirrhosis. Only 1 patient among those with persistent viral hepatitis had delta-antibody, whereas 18 with chronic active hepatitis had delta-antibody in their sera (p less than 0.05).