Aqueous, ethanolic and petroleum ether extracts of Citrus sinensis L. (Osbeck), Euphrasia officinalis L., Glycyrrhiza glabra L., Matricaria recutita L., Rosa canina L. and Ruta graveolens L. have been studied. The cytotoxicity of the drugs assayed was evaluated "in vitro" by means of the dye test using cells of the Yoshida ascites sarcoma. The aqueous extract of Citrus sinensis L. (Osbeck); the petroleum ether extract of Glycyrrhiza glabra L.; the ethanolic and petroleum ether extracts of Rosa canina L. and the petroleum ether extract of Ruta graveolens L. showed a quite significative cytotoxic effect.