Sera from patients with acute or early and chronic schistosomiasis were examined for IgG, IgM, and IgE antibody by an enzyme-linked immunosorbent assay technique, using soluble egg antigen from Schistosoma mansoni. Cercarial/adult IgG antibody ratios were determined, using soluble cercarial and adult worm antigens. Sera with cercarial/adult ratios indicative of acute or early schistosomiasis also contained specific IgM antibodies. Schistosome IgE antibody was found in sera from patients with acute schistosomiasis, but in only 1 of 10 sera from patients with chronic schistosomiasis. The inability of ELISA to detect IgE antibodies in chronic sera indicates that it may be a relatively insensitive measure of IgE antibodies in those patients with chronic schistosomiasis.