This study was designed to assess the anxiolytic effects of Costus afer in rats. The aqueous extract of the plant is used in Cameroon traditionally in hepatocellular protection, as an anti-hyperglycemic, a central nervous system depressant, an analgesic and an antioxidant. Ninety rats were partitioned into 6 groups and treated as follow: Group 1 received distilled water; groups 2, 3, 4 and 5 were treated with C. afer (100, 250, 500 and 1000 mg/kg) respectively; and group 6 received either diazepam or phenobarbital. One hour post-treatment, Stress-induced hyperthermia, elevated plus maze and open field were the rodent behavioural models used in this study. Some biochemical parameters were analyzed and brain histological sections examined. Results showed that, C. afer (500; 1000 mg/kg) decreased stress-induced hyperthermia at 0.3°C compared to 0.6°C in the negative control. In the elevated plus maze, C. afer (500 mg/kg) significantly increased the percentage of open arms entries to 72.8 % compared to 24.15 % recorded in the group 1 animals. In the open field, C. after (1000 mg/kg) raised the number of crossings from 8 ± 00 in the group 1 animals to 39.6 ± 5.8. C. afer (1000 mg/kg) significantly (P < 0.001) increased GABA level from 267.67 μg/g of tissue in the group 1 to 392.6 μg/g of tissue. The plant protects brain against stress-induced pyknosis of neurons. Its antipyretic and anxiolytic activities in rats could be used in traditional medicine to treat fever and anxiety.