To better define the relationship between suppressor cell function and number and disease expression, the immunoregulatory profiles of 12 probands with systemic lupus erythematosus (SLE) and 34 of their asymptomatic family members were studied, using concanavalin A induced suppressor cells for functional analysis. SLE family members as a whole showed no impairment of mean suppressor levels, although 7 of 34 had altered suppression of DNA synthesis and 5 of 34 had altered suppression of IgG synthesis. Ratios of OKT4/T8 T cell subsets showed no difference between the study population, although 3 SLE family members had an increased ratio (greater than 2 SD) relative to controls. The 12 family members with either altered suppressor cell number or function had higher antibody levels to dRNA (Poly A . U) than did those with normal suppressor function and number. The results demonstrate that altered suppressor cell number and function occur in certain asymptomatic family members of SLE patients and may be weakly associated with markers of a preceding RNA viral infection.