The pattern of cuticle protein synthesis during development of the nematode Caenorhabditis elegans has been studied using NaH14CO3. Both pulse-labeling and pulse-chase-labeling experiments indicate that synthesis of cuticle components occurs at high levels during the molting periods and at much reduced rates during the intermolt periods. No such discontinuous pattern is observed for the synthesis of total noncuticle macromolecules during development. The soluble and insoluble proteins of the cuticle, which comprise the inner and outer cuticle layers, respectively, follow similar patterns of synthesis during the two molts examined. At each molt the structural components of the cuticle account for approximately 10% of the total macromolecules labeled by NaH14CO3. No evidence is found for reuse of cuticle material between successive developmental stages of C. elegans.