Two lionesses, 13 and 14 years old, were presented for Traditional Chinese veterinary medicine (TCVM) evaluation and treatment for aggression, unresponsive to conventional pharmacological therapy of 5 months duration. The lionesses had previously co-existed without such altercations for 12 years. Emotional and environmental stressors included the loss of the male exhibit mate 8 months earlier, the transfer of 7 big cats in and out of the communal cathouse over the previous 2 years, the general stress of captivity in a wild exotic species and unusually Hot Damp summer weather. Both lionesses were diagnosed with Liver Qi Stagnation and Liver Yang Rising. Animal care personnel rated the aggression of each animal, on a defined scale of 0-5 for 11 days prior and 14 weeks during treatment with the veterinary Chinese herbal medicine, Liver Happy (modified Chai Hu Shu Gan Wan). The average aggression score prior to and during the 14-week treatment period were compared and an 84.25% improvement in aggression was found for Lioness 1 and 95.88% improvement was found in Lioness 2. Although a limited TCVM examination can be performed on wild exotic cats, with the correct TCVM pattern diagnosis based on history, clinical signs and tongue color, administration of the appropriate Chinese herbal medicine may result in the rapid resolution of some forms of aggression.