The present study aimed at investigating the efficiency of a recent antibiotic Aminosidine sulphate (Gabbroral) in experimental cryptosporidiosis. The course of infection was studied when the drug was given early before the infection, and late during the infection both parasitologically and histopathologically. When the drug was given early, the results were satisfactory, with a significant reduction of size, number and pathological changes of the parasites in the stool and in ileal sections of infected mice. However, the drug had no effect when given late during the infection.