SUMMARYFour groups of children were tested for the distribution of C3 and BF phenotypes: HBV‐infected patients with Gianotti‐Crosti syndrome, with CAH and with glomerulonephritis, and healthy children. The frequency of the phenotype C3F was significantly higher in children with Gianotti‐Crosti syndrome in comparison with healthy children. The frequency of the phenotype BFS was significantly higher in patients with glomerulonephritis than in individuals with CAH. The difference between the frequency of the BFS phenotype in glomerulonephritis patients and that in healthy subjects neared significance. We suggest that the carriers of these phenotypes are characterized by susceptibility to some immune complex diseases associated with HBV infe