Four medicinal plants--Tecoma stans, Ligusticum porteri, Monarda austromontana, and Poliomintha longiflora, which are distributed in tropical and subtropical countries of the American continent--are widely used in folk medicine to treat diseases such as diarrhea and dysentery. In addition, T. stans and P. longiflora are extensively used as hypoglycemic agents, and M. austromontana and P. longiflora are used as condiments. The plants were collected, identified, dried, and pulverized. Solvent extraction was prepared by maceration of the plant samples, and the phytochemical composition of the extracts was determined by using standard analysis procedures. Phytochemical analysis showed the presence of triterpenoids/steroids, flavonoids, and phenols/tannins and, in L. porteri, traces of alkaloids. After the elimination of solvents in vacuo, the extracts were administrated to Drosophila larvae to test their toxicity and genotoxicity. Third instar larvae were chronically fed with the phytoextracts. The extract from L. porteri was toxic, whereas those from T. stans, P. longiflora, and M. austromontana were not. Genotoxic activities of the 4 plants were investigated by using the wing-spot assay of D. melanogaster. Mitomycin C was used as a positive control. No statistically significant increase was observed between treated sample series and a concurrent negative (water) or solvent control sample series.