To the Editor: In the issue of September 10, 1970, Leroy and Spranger refer to multiple lysosomal enzyme deficiency in cultured fibroblasts from a patient with "I-cell disease."1 In one of our patients who had clinical symptoms suggesting "I-cell disease" we have also found decreased levels of a number of lysosomal enzymes in cultured fibroblasts. The patient had a "Hurler-like" appearance, combined with minimal skeletal deformities, inguinal hernia and mild psychomotor retardation. No hepatosplenomegaly was noted. Urinary secretion of mucopolysaccharides (MPS) was normal. Lymphocytes in the peripheral blood and cells in smears of bone marrow showed vacuolization.Fibroblasts grown from . . .