This study was carry out in the stored grain insects laboratory of Faculty of Agriculture, CairoUniversity throughout August 2008 to February 2009 to associate the insect populations with stored hazelnuts, determine the percentages of infestation on hazelnuts and percentages of weight losses in the infested nuts. Four species of stored-product pests were recorded, the sawtoothed grain beetle, Oryzaephilus surinamensis, the rust-red flour beetle, Tribolium castaneum, the Indianmeal moth, Plodia interpunctella and the cigarette beetle, Lasioderma serricorne. One predatory Hemiptera and another one Hymenoptera parasite were found during study to have potential for biological pest control. During storage period, the mean number of adults of four species were the highest in Sept. and Oct., after that the populations decreased gradually with increasing the storage period which reached the lowest number of adults in Feb. The percent of infestations were 50.03, 56.6, 60.63, 63.15, 57.75 and 54.35% during Sept., Oct., Nov., Dec., Jan., Feb., respectively. The corresponding values of losses in weight of nuts were 25.43, 27.2, 32.28, 21.53, 18.0 and 16.28%. Under artificial infestation levels, P. interpunctella was more effective for weight losses of nuts followed by T. castaneum then O. surinamensis. Weight losses ranged to 6.64 – 18.83, 1.6 – 6.55 and 0.87 – 3.42 % for Plodia interpunctella, Tribolium castaneum and Oryzaephilus surinamensis, respectively.