In the present study, a Nucleopolyhedrovirus (NPV) was isolated from laboratory-reared larva of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Under the light microscope, high numbers of polyhedral inclusion bodies (PIBs) formed by the virus were found in hemolymph, tracheae, and the midgut. The PIBs measured 1.97 +/- A 0.46 (1-3.04) A mu m (n = 50). In cross-sections of PIBs, the virions contain a high number of nucleocapsids (1-28), and the viral particles were 190-270 x 30-40 nm. Some diamond-shaped inclusion bodies, like spindles, which did not include virions, were also observed. This virus was isolated and characterized for the first time from E. kuehniella.