The antifungal and antibacterial activity of 10 crude extracts from four different species, all of them used in Mexican folk medicine for the treatment of infectious diseases, were tested in vitro. for antimicrobial activity against Staphylococcus aureus., Streptococcus faecalis., Escherichia coli, Klebsiella pneumoniae., Salmonella typhi., Candida albicans., Trichophyton mentagrophytes., and Trichophyton rubrum.. All extracts from the above plants showed some degree of antimicrobial activity against at least two microorganisms tested. The strongest antibacterial activity was found in the water extract of Hibiscus sabdariffa. and the methanol extract of Lysiloma acapulcensis., whereas the methanol extract from Loeselia mexicana. showed the best antifungal activity against dermatophytes.