Laboratory bioassay studies were conducted to determine the effects of 9 isolates of Beauveria bassiana and one isolate of Metarhizium anisopliae isolated from the soils in Isparta, Turkey, against Helicoverpa armigera (Hubner), Spodoptera littoralis (Hubner) (Lepidoptera: Noctuidae), Tenebrio molitor (L.) (Coleoptera: Tenebrionidae) and Blattella germanica (L.) (Blattodea: Blattellidae). Concentrations of 2x10(7) conidia/mL were applied on insects by hand sprayer. All treated insects were incubated at 26 +/- 1 degrees C, 70 +/- 5% relative humidity for 12 days. All entomopathogenic fungi were infectious to all tested insects but infection rates were different. Isolates of B. bassiana and M. anisopliae showed very low infection rates on B. germanica (3.3-6.7%). Other insects had different mortality rates. H. armigera, S. littoralis and T. molitor had 53.3-73.3%, 56.7-66.7% and 73.3-80.0% infection rates, respectively. As all fungal isolates were not very effective on a germanica under laboratory conditions but showed effectiveness on other insects.