Although Turkey is the first among all hazelnut-producing countries, yield per unit area of this crop is low in comparison to other countries, mainly because many insect species seriously damage hazelnut trees and their fruit. To find effective and safe biocontrol agents, we conducted a survey study to isolate entomopathogenic fungi from the hazelnut-growing region of Turkey and characterized the isolated strains in detail. In addition, we determined the effectiveness of seven selected strains from this region against Melolontha melolontha (Coleoptera: Scarabaeidae) which is one of the most serious pests of hazelnut. In 2006 and 2007, 301 soil samples were collected randomly and analyzed for presence of entomopathogenic fungi using the Galleria bait method. Entomopathogenic fungi were found to occur in 20.59% of the soil samples studied. Based on morphology, ITS sequence and partial sequencing of the 18S (SSU rDNA) and EF1-alpha genes, the isolates were identified as Metarhizium anisopliae var. anisopliae, Metarhizium sp., Beauveria bassiana, Beauveria cf. bassiana, Isaria fumosorosea and Evlachovaea sp. Metarhizium anisopliae var. anisopliae was isolated from 34 sites and was the most frequent and abundant entomopathogenic species recovered. All the isolates tested were pathogenic to M. melolontha. M. anisopliae var. anisopliae KTU-27 and Evlachovaea sp. KTU-36 produced the highest insecticidal activity (86.6%) within 15 days after inoculation. Our results suggest that entomopathogenic fungi could be good biocontrol agents against M. melolontha, and are discussed with respect to ecology of fungi in relation to habitat in order to evaluate biocontrol potential of these isolates. This is the first study of the distribution of entomopathogenic fungi in the hazelnut-growing region of Turkey and of their pathogenicities against M. melolontha.