This study indicates that Leucas aspera and Glycosmis pentaphylla extracts have good antipyretic activity. Ethanolic extract of Leucas aspera and Glycosmis pentaphylla exhibited significant anti-pyretic activities in Brewer’s yeast induced pyrexia in rats. The maximum antipyretic activity throughout the test period of 6 hours was produced by ethanolic extract of plant Leucas aspera (200 mg/kg) and standard (paracetamol treated) group. In general, nonsteroidal anti-inflammatory drugs produce their antipyretic action through the inhibition of prostaglandin synthetase within the Hypothalamus. Therefore, the antipyretic activity of extracts of Leucas aspera and Glycosmis pentaphylla is probably by inhibition of prostaglandin synthesis in hypothalamus.