Abstract: By the modified Siegmund method, we showed that the extract of Nerium indicum Mill.inhibits the spontaneous activity of mice.Again,barbital-induced sleeping time may be prolonged and the action of caffeine and amphetamine on the activity of mice may be also antagomisted. These results indicate that Nerium indicum Mill. has a definite sedative action.On the other hand,it has no protective action on the chemical and electrical seizures of mice. The genin of Nerium glucoside has also a sedative action and after the great part of glucoside is excluded from the extract,the sedative dose of Nerium is also adequately increased.It is,therefore,quite possible that the sedative fraction present in Nerium indicum Mill.is the glucoside or the genin of glucoside.