This study presents the hematologic parameters of 29 captive lions (Panthera leo) and 16 captive Siberian tigers (Panthera tigris altaica) from the Zoological Park of São Paulo Foundation. For inclusion in the experiment, animals were clinically examined, and those with recent physiological and/or concurrent alterations, those who were receiving any type of medication, those with an inadequate body condition score, those with dehydration, and those infested by ectoparasites or affected by some disease were excluded. The animals were chemically restrained on their own premises using anesthetic darts containing ketamine and xylazine. Blood samples were collected by jugular, cephalic or saphenous venipuncture. The appropriated volume intended for a hemogram evaluation was collected in tubes containing 2.7 nM Na2 EDTA, to preserving the ideal ratio of blood to anticoagulant. For statistical analysis, Unpaired Student t tests were performed and P < 0.05 was considered statistically significant. No significant differences were found in the hematological values between male and femalelions, except for the mature neutrophils values, which was higher in males.[...](AU)