Eight clinically normal calves of different breeds were used in this study. The animals were given daily doses of arsanilic acid (Pro-Gen Abbott) varying from 1.4 to 6 mgs/lb. of live body weight with subsequent individual increase up to 20 mg/lb. Daily physical examination were carried out on each animal. Samples of blood and urine were taken two or three times a week for analysis. After death, tissues were collected for histopathological examination. Following is a description of the most important findings: 1) Arsanilic acid, in this study, did not show the growth promoting properties for calves reported for poultry and swine. 2) The toxic level of arsanilic acid for calves is 8 mgs/lb. of body weight. 3) Bilirubinemia, bilirubinuria and albuminuria occurs on the last two or three days preceding death. 4) Prothrombin time is gradually increased from the first ingestion of arsanilic acid reaching the highest values two days before death. Increases in prothrombin time occurred even on low levels of arsanilic acid which produced no other clinical or clinical pathological changes. 5) Symptoms and pathologies-anatomical lesions are similar to those reported for other arsenic derivatives. 6) Principal organs injured are the liver and kidney. / Master of Science