An outbreak of footrot occurred in a flock of Corriedale sheep; 27 animals were treated with antibiotic and footbathed in a 5% copper sulfate solution. Being deprived of water for > 17 h, many sheep drank the footbath solution. After 6 h 16 sheep became ill with acute copper poisoning, 10 animals died within 10 h; 6 were severely ill and were sent to Veterinary Hospital, and 4 had mild signs and recovered without treatment. The sick sheep had anorexia, dullness, grinding teeth, moaning, rumen atony, dehydration, dark blue-green diarrheic feces and congested membranes. They were treated with 3.4 mg tetrathiomolybdate/kg body weight and lactated Ringer's solution iv, oral molybdate, sulfate, kaolin and pectin, and drenched with antacids. Two of the 6 sheep died during hospitalization. The ingestion of copper solution caused an intense gastrointestinal injury that resulted in ulcers, petechial and echymotic hemorrhages in the mucosa, mild hemolysis detected by microscopic hemoglobinuria and a lowered packed cell volume, severe hepatic injury that raised the AST and gammaGT blood values, and moderate kidney lesions with increasing serum blood urea and nitrogen creatinine levels.