The polyherbal formulation, Ilavangathi choornam, a Siddha formulation had been analysed for its anti- histamine activity by guineapig ileum preparation. The test d rug Ilavangthi choornam is administered as 1mg/ml. The concentration-response curve of histamine and its m odification by the test drug is recorded by kymogra ph. In this study, response of histamine which contracts smooth muscle is decreased after the administration of te st drug which shows that the given sample may have a smooth muscl e dilating property.