Analysis of segregation and heritability were performed, with the aid of Penrose's method, maximum likelihood estimation and Falconer's method, in 215 cases with systemic lupus erythematosus (SLE) and their pedigrees to explore its possible model of inheritance. Results showed that prevalence of SLE in first-degree relatives of the proband with SLE was 0.85% and higher than that in general population (0.03%). A ratio of s/q approached 1/square root q with Penrose's method, segregation proportion was equal to 0.029 with simple segregation analysis, with a chi-square for goodness-of-fit of 0.0001 (P > 0.05), and the heritability of SLE was 56.7% (P < 0.05). It suggests that SLE follows a pattern of multifactorial inheritance rather than single-gene one.