Abstract: Various parts of the Jatropha curcas plant are of medicinal value, its wood and fruit can be used for numerous purposes including fuel. In the present study the effectiveness of Jatropha curcas oil on inactivation of some mycoflora were determined. As a measure of testing the antimicrobial property of Jatropha curcas oil were subjected against six selected fungi viz. Alternaria alternata, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium chlamydosporum and Penicillium glabrum. Poisoned food technique was used to evaluate the antifungal effect of J. curcas oil. Two different concentrations of Jatropha oil i.e., 100 μL and 500 μL were mixed with potato dextrose agar (PDA) medium in Petri plates. Maximum radial growth was shown by control of Aspergillus flavus, Aspergillus fumigatus and Aspergillus niger i.e., 90 mm (full growth on petri plate) followed by the control of Alternaria alternata i.e., 77.3 mm and minimum growth was shown by Penicillium glabrum i.e., 21 mm followed by Aspergillus niger i.e., 33 mm at 500 μL concentration of Jatropha oil. Maximum percent inhibition was shown by Penicillium glabrum i.e., 82.96% followed by Aspergillus niger i.e., 63.33% at 500 μL concentration of Jatropha oil and minimum percent inhibition was shown by Fusarium chlamydosporum i.e., 31.59% at 100 μL concentration of Jatropha oil. From this experiment it was concluded that Jatropha oil has promising antifungal effect on Penicillium glabrum and Aspergillus niger.