Cannabis sativa L. is a medicinally important plant, generally grows as a weed in waste lands in Punjab, Pakistan. In the present study, antifungal effect of leaf extract of this weed was assessed against Aspergillus flavipes. Methanolic leaf extract of the weed was partitioned into five fractions using organic solvents of variable polarities. A range of concentrations (1.562 to 200 mg mL-1) of each fraction was used in laboratory bioassays. n-Butanol fraction showed the highest antifungal activity followed by chloroform and n-hexane fractions causing 68–82%, 52–82% and 42–82% decrease in biomass of A. flavipes. Ethyl acetate showed a moderate antifungal potential whereas aqueous fraction showed the least antifungal activity causing 47–76% and 38–73% reduction in fungal biomass, respectively. This study concludes that n-butanol fraction of leaf extract of C. sativa is highly effective in controlling growth of A. flavipes.