The patterns of protein synthesis associated with three sequential stages in protoplast morphogenesis (spindle-shaped, early fusion sphere, and late fusion sphere protoplasts) of the fungus Entomophaga aulicae were studied using both one-dimensional gels with general protein staining and two-dimensional gels with [35S]methionine protein labelling and fluorography. A total of 332 proteins were observed with 63.5% (211) common to all three developmental stages. Of the individual totals, 3.3% (8 out of 245), 7.3% (22 out of 301), and 4.5% (13 out of 286) of the proteins were unique to the spindle-shaped, early fusion sphere, and late fusion sphere protoplasts, respectively. The molecular mass and pI distribution profiles for early fusion sphere protoplast proteins are discussed.Key words: protein synthesis, stage-specific proteins, fungal protoplasts, Entomophaga aulicae.