The in vitro addition of mite or human unparasited scale extracts to the serum of 8 patients with scabies and 5 healthy controls did not significantly modify the fixation of 125I-C1q as compared to control tubes (serum with physiological saline). These results suggest that antigens or substances derived from the scabies mite are not involved in the immune complexes present in the serum of the parasited patients.