The sera of school children with Schistosoma haematobium infection were tested for the presence of cold-insoluble immune complexes "the cryoglobulins". Two different methods were used: the standard macro-technique and the micro-adaptation technique. On using the standard macro-technique, 40 (32.8%) out of 122 schistosomiasis patients and 6 (7.5%) out of 80 control children were positive for cryoglobulins. Using the micro-adaptation technique, the corresponding numbers were 47 (38.5%) and 8 (10%), respectively. A comprehensive medical examination was carried out before treatment. After treatment with metrifonate (Bilarcil) the quantity of cryoglobulins and the number of children with cryoglobulins were significantly reduced to 12 (9.8%) when using macro-technique, and to 15 (12.3%) with micro-adaptation technique, thus suggesting a possible relationship of cryoglobulinaemia with urinary schistosomiasis. There was a significant difference in the number of sera found positive by the two techniques (X2 = 0.875, P less than 0.1).