During antidermatophytic investigations of the plant secondary metabolites of some common ethnomedicinal plants, the essential oil of Curcuma longa Linn (family Zingiberaceae) was found to be the strongest toxicant against the pathogenic fungi Trichophyton mentagrophytes and T. rubrum, dermatophytes causing ringworm infection in human beings. The minimum inhibitory concentration (MIC) of the oil was recorded at 1.9 mg/ml against T. mentagrophytes and 2.1 mg/ml against T. rubrum. However, it was fungicidal at 2.4 mg/ml against T. mentagrophytes and 2.5 mg/ml against T. rubrum respectively. The effective concentration contains heavy doses of inoculums (25 discs of 5 mm each.). The minimum killing time (MKT) of the oil was 45 sec against T. mentagrophytes and 30 sec against T. rubrum, while it’s MFCs required 7.00 hrs against T. mentagrophytes and 5.30 hrs against T. rubrum. The efficacy was thermo stable up to 80°C and for 36 months of storage, the maximum unit taken into consideration. Moreover, the oil did not exhibit any adverse effect on human skin up to 5% conc. Further detail in vivo investigations as well as clinical trial are required with the formulation(s) of the oil to fully develop an alternative to the synthetics.