Six pediatric patients with Niemann-Pick disease are reported. They have been studied at Hepatology Unit HI "La Paz" (Madrid) in the period of time between 1975-1988. They are one case of type A, one case of type B and four cases of type C. This group of pediatric patients serve us to make a revision of the disease attending to clinical and biochemical classification aspects, diagnosis and treatment. We insist on two aspects: 1) greater importance of enzymatic diagnose for the "Niemann-Pick complex", in view of the overlapping of clinical symptoms, 2) bone-marrow transplantation as therapeutic alternative and its indications.