Effects of five essential oils (Cinnamon, Garlic, Mint, Rosemary and thyme) that seemed to have powerful antifungal and antiaflatoxin characteristics on Aspergillus parasiticus were studied in this research. A. parasiticus is one of the most important species that produces aflatoxin in walnuts. We used three concentrations from each tested essential oils (1,2 ,4). The all tested essential oils appeared more effectiveness on the  growth  and aflatoxin B and G at three tested concentrations compare to control. Cinnamon oil at 4 % was the highest effective essential oils on inhibition aflatoxin B and G were ranged from  62.7 to 71.0  and 46.4 to 74.4 % and 58.2 to 69.1%, respectively followe by and thyme oil . Mint and Rosemary oil gave moderate effect  while garlic oil was the least. As well as aflatoxin was extracted from samples of walnuts then determined by high performance liquid chromatography (HPLC). Their concentrations ranged from 27.8 to 105.1 µg/kg. The highest levels were found in sample no.4.