Lymphocyte subpopulations identified by OK3, OK4 and OK8 monoclonal antibodies were studied as a function of certain Rh markers in 2 groups of subjects: 47 children and adolescents with proven reaginic IgE-dependent allergies and 29 healthy adult controls. The Rh antigens C and c were evaluated in their 3 possible configurations: CC, Cc and cc. In both groups studied, the same significant distribution was observed. Allergic cc subjects had the most CD4+ lymphocytes (43.4%) versus CC (34%) and Cc (33.7%), as compared to control cc (42.05%), CC (36.1%). The possible clinical implications of these findings are discussed.