The mutagenic activities of the pyrolyzates (300, 600, 750 and 85$0^{circ}C$ ) of extracts from three saponeous expectorants (Platicodi Radix, Polygalae Radix and Asiasari Radix) and two nonalkaloidal antitussives (Lirionis Tuber and Codonopsis lanceolata Radix), medicinal plants, were studied in the Ames Salmonella/microsomes test system. The pyrolysates of Codonopsis lanceolata Radix and Asiasari Radix extracts at 85$0^{circ}C$ were slightly mutagenic to tester strain TA98( frame shift ) and TA100(base-pair substitution) of Salmonella typhimurium, and the mutagens in these pyrolyzates required the metabolic activation by a liver microsomal fraction However, the extracts and pyrolyzates of all medicinal plants tasted except the above two results dud not show the significant increase in revertant colonies.