Ovarian development and vitellin of the mushroom fly, Lycoriella mali, were characterized. L. mali has a pair of ovaries, composed of 50-60 ovarioles, respectively. Ovarian development began at 1 day of pupation, and continued to become mature at 2 days after adult emergence. The vitellogenin (Vg) and vitellin (Vn) of L. mali were identified by native - and SDS-PAGE analyses. The Vn is composed of two subunits with a large subunit, L-Vn(190 kDa), and a small subunit, S-Vn (63kDa), respectively. These two subunits of Vn gradually decreased in content during embryogenesis. We confirmed the presence of the Vg and Vn which were first detected in the 3 day-old female pupae by SDS-PAGE and Western blot analyses. It can be assumed that the Vn is synthesized as a precursor (Vg) in the fat body at 3 days after pupation and released into hemolymph. Then, the Vg is subsequently absorbed into the ovary at the same time. Twelve amino acid residues after the signal peptide at the -N-terminus of .mali S-Vn were sequenced and showed 80% homology to those of Anthonomus grandis vitellogenin.