Juliflorine, an alkaloid from Prosopis juliflora, was tested for its antifungal activity against the freshly isolated cultures of dermatophytic fungi and its inhibitory effect was compared with that of griseofulvin. The results indicated that the minimum inhibitory concentration (MIC) of juliflorine against Trichophyton rubrum, Trichophyton violaceum, Trichophyton mentagrophytes, Trichophyton tonsurans, Trichophyton megninii, Trichophyton gallinae, Microsporum canis, Microsporum nanum, Microsporum ferrugineum and Epidermophyton floccosum was 1.5 micrograms/ml, whereas that of griseofulvin was 0.1-0.5 microgram/ml. MIC of juliflorine for Candida albicans was 0.05 mg/ml. The alkaloid was also subjected to screening for carcinogenicity in the Ames test (salmonella/microsome test system). The results indicated that the compound in the recommended concentrations did not exhibit positive mutagenic reaction, as compared to a strong positive reaction by ethyl methane sulfonate based on his- ----his+ revertants.