Proteins, soluble in 7 M urea, 4 M guanidine hydrochloride, or 2% sodium dodecyl sulfate, were extracted from untanned larval cuticles of D. melanogaster. A major protein fraction, apparent MW 8000-10,000, was resolved into 8 different components (5 major, 3 minor) by gradient gel electrophoresis under nondenaturing conditions. Proteins extracted in 7 M urea were resolved by DEAE-cellulose chromatography into 5 fractions, 3 of which were greatly enriched from electrophoretically homogeneous proteins. The 5 fractions had different amino acid compositions. Electrophoretic variants involving 4 of the 5 major proteins were obtained. Preliminary genetic analysis indicated that at least 3 of the 5 proteins were specified by separate structural genes.