Four healthy cats were given clindamycin orally in daily doses of 25 or 50 mg/kg of body weight for 6 weeks. Significant change in Factor-VII activity was not found, compared with pretreatment values. In 2 cats tested, toxin produced by Clostridium difficile was not detected in fecal samples obtained before treatment and at 6 weeks after treatment, suggesting that intestinal overgrowth by C difficile did not develop. Results of the study seemed to indicate that orally administered clindamycin does not measurably reduce synthesis of vitamin K-dependent clotting factors in healthy cats.