The ethanolic extract of some medicinal plants having anti-asthmatic activity such as Solanum xanthocarpum, Curcuma longa, Glycyrrhiza glabra, Piper longum, A. vasica, A. lebbeck, and Tinospora cordifolia was evaluated for antihistaminic and anti-cataleptic activity. The aqueous solution of ethanolic extract of S. xanthocarpum and G. glabra potentiated histamine-induced tracheal chain contractions. Whereas, C. longa, P. longum, and T. cordifolia, and A. lebbeck were without any significant effect on histamine. Only A. vasica inhibited histamine-induced tracheal chain contraction. G. glabra per se produced contraction of the tracheal chain, which was blocked by pretreatment with atropine. Single dose of S. xanthocarpum potentiated clonidine-induced catalepsy but on repeated doses (once in a day for 3 days) inhibited catalepsy. Pretreatment with ethanolic extract of C. longa, P. longum, T. cordifolia inhibited catalepsy whereas G. glabra and A. lebbeck significantly potentiated clonidine-induced catalepsy. None of the extracts inhibited haloperidol-induced catalepsy. Thus the extracts having antihistaminic activity or mast cell stabilizing activity inhibited clonidineinduced catalepsy.