A simplified version of the magnetic bead antigen-capture enzyme-linked immunoassay (MBAC-EIA) was used to detect circulating anodic antigen (CAA) in individuals of different age groups with Schistosoma haematobium infection only in an endemic area of Zimbabwe. An overall positive correlation between S. haematobium egg excretion and CAA levels was demonstrated. The age profile for CAA levels was generally comparable with the age profile of S. haematobium prevalence and intensity of infection. The CAA levels were higher in younger (5-14 years of age) individuals than in older (greater than 14 years of age) ones. Since the sensitivity of the MBAC-EIA in the diagnosis of S. haematobium infection was found to be 97%, CAA levels appear to be a useful indicator of worm burden in an endemic area.