An AIDS patient with severe large volume diarrhea and malnutrition due to cryptosporidial infection is presented. The patient, who was not receiving zidovudine, was treated with octreotide with resolution of diarrhea leading to improvement in nutritional status, immune functions, and subsequently, resolution of the Cryptosporidium infection. This case points out the need for adequate nutrition in AIDS patients and highlights the relationship of nutrition and the immune system.