Cell-mediated and humoral immunity were investigated in 18 patients with West syndrome, 12 with Lennox-Gastaut syndrome and 19 healthy controls. The study included determination of Ô and  peripheral blood lymphocytes, serum levels of IgG, IgA and IgM, skin sensibilization with DNCB, intracutaneous PHA, leucocyte migration inhibition test and lymphocyte blastic transformation in the presence of PHA. Cell-mediated deficiency was detected in 28 children whereas low levels of immunoglobulins were observed only in 6 children. Immunological disturbances were more prominent in children with West syndrome.