The aqueous and ethanol extracts of Stichopus chloronotus Brandt were investigated for their effectiveness against guinea pig dermatophytosis caused by Microsporum canis and Trichophyton mentagrophytes using the hair root invasion test. The ethanol extract at 10 mg/ml showed 82.8 % efficacy against T. mentagrophytes while the aqueous extract at similar concentration showed 84.8% efficacy against M. canis infection, as compared to econazole which showed 100% efficacy against both infections. No adverse effect on the skin was observed in the treated animals. In conclusion, aqueous and ethanol extracts of S. chloronotus showed high antimycotic activity against experimentally induced dermatophytosis in guinea pigs.