Two hundred and fifteen schizophrenic patients (108 males and 107 females) in north-east England have been investigated for Gc types and subtypes and compared with the frequencies in first-degree relatives and controls. Böök et al. (1978) described Gc2 allele association with schizophrenia. No such association was found with the Gc2 allele in the present study although there is a tendency towards an increased frequency in females. In subtype allele frequencies the female patients showed a significant reduction of Gc1S allele. The results suggest a difference in susceptibility associated with the Gc locus in patients of different sexes.