Young quails kept in wire-floored cages experienced high mortality, beginning at age 5 days, from diarrhea that was unresponsive to antibiotic therapy. At necropsy, the small intestine had clear fluid content and the cecum was distended by brown foamy fluid. Histopathologic findings in the small intestine were shortened villi with detached enterocytes at the tip. Cryptosporidium sp. (confirmed by electron microscopy) were numerous in the microvillous border. Neither bacterial nor viral pathogens were detected. No infection was established in day-old chickens gavaged with feces and intestinal contents from infected quails. Thorough cleansing of the cages followed by application of commercial bleach prevented recurrence.