Presented here is a 17-month-old adenosine deaminase-deficient, severe combined immunodeficient patient with chest symptoms, oral ulcer, neurologic manifestations, head lag, spasticity and developmental delay in motor functions. Antibiotics, systemic antifungal agents, intravenous immunoglobulins and partial exchange transfusions with irradiated fresh red cells were given. No other mode of therapy for adenosine deaminase (ADA) deficiency was available at that time. Amelioration of neurologic manifestations within one month of therapy with irradiated fresh red cell exchange transfusions suggests that these manifestations may have resulted from accumulated toxic metabolites. However, no improvement was seen in the course of infection and oral ulcer, and the patient died of respiratory failure on the 48th day of admission.