Objective 　To assess the association between the gene of complement C4A, C4B deficiency and schizophrenia. Methods　192 patients with schizophrenia and 142 healthy controls were tested with the amplification restriction fragment length polymorphism (Amp-RFLP) technique.Results　The frequency of C4AQ0/C4AQ0 homozygote was higher in the patient group than in the control group (χ2=8.54, P＜0.01). The relative risk (RR) of C4AQ0/C4AQ0 homozygote for schizophrenia was 6.8. There was no increased frequency of C4B deficiency in patients with schizophrenia (χ2=0.11, P＞0.05, RR=0.73).Conclusions　These results indicate that there is a positive association between complement C4A dificiency and schizophrenia. Moreover, our study did not support a widespread association between a deficiency in complement component C4B and schizophrenia.