The alder leaf beetle, Agelastica alni L. (Coleoptera: Chrysomelidae) is one of the most dangerous defoliator pests of Alnus spp., Corylus spp., Populus spp. and Salix spp. worldwide. In order to discover a significant biocontrol agent against this pest, thirteen local entomopathogenic fungal isolates were screened against different growth stages of A. alni with dose of 1 x 10(7) conidia under laboratory conditions. These included four isolates of Beauveria bassiana (Bals.) Vuill., seven isolates of Metarhizium anisopliae (Metsch.) Sorokin, one isolate of Myriodontium keratinophilum Samson and Polon and one isolate of Isaria fitmosorosea (Wize) Brown and Smith. The B. bassiana isolate KTU-24 showed the highest mortality rate (100 %) at all stages of A. alni within 14 days after inoculation. Dose mortality response bioassays showed that B. bassiana isolate (KTU-24) had the highest mortality rate (100 %) against 1st, 3rd instar larvae and adults of A. alni within 14 days after inoculation. These results indicate that B. bassiana KTU-24 seems to be a promising candidate for further studies as a biocontrol agent against A. alni.