In recent years, there has been a search for alternatives to fungicides that would provide satisfactory mycotoxin control featuring low environmental impact and low toxicity to human beings. Neem, Azadirachta indica A. Juss (Meliaceae), is a plant species with natural fungicide compounds. Current study evaluates the effects of the aqueous extract from leaves and oil of Neem seeds on Aspergillus nidulans iA1 and Penicillium cyclopium cultures. Sterigmatocystin production by Aspergillus nidulans was inhibited during cultivation when culture medium contained 1.50 and 3.00% of oil of Neem seeds. Oil from Neem seeds had no significant effect on radial growth and reduced the sporulation of Aspergillus nidulans. It significantly increased radial growth, although no significant effect on the sporulation of Penicillium cyclopium was detected.