Cassia siamea Lamk. (Johar) leaf is one of the Indonesian medicinal Simplicia which is empirically used by some people to overcome malaria disease. Traditional use of johar leaf against malaria disease might be effective to kill the malarial parasites or to reduce fever, because people who are suffering from malaria produce fever. This paper reports the antipyretic effect of the 70 % etanol extract of the johar leaf on the artificial fever in albino rats induced by chotypha vaccine. The result show that a dose of 3 mg/100 g b.w. of rat (equivalent to one thirths of man dose ) has antipyretic effect equivalent to acetosa! 30 mg/100 g b.w.