Abstract Two hundred subjects with no evidence of rheumatoid arthritis, but presenting a positive latex fixation test (LFT), were studied for presence of the already described conditions associated with the presence of rheumatoid factor. One hundred controls were similarly studied. The incidence of hepatomegaly, hypergammaglobulinemia and positive skin test for schistosoma mansoni was found higher in positive LFT subjects than controls. This triad is the characteristic feature of schistosomiasis in our population. The results obtained tend to implicate schistosomiasis mansoni as a contributory cause for false positive LFT, on the basis of the liver abnormalities caused by this condition.