Diploid fibroblast strains were established from explants of normal gingiva from donors ranging in age from 12 to 68 years. By using labeled amino acid precursors, we measured protein and collagen production, and intra- and extracellular protein degradation. Qualitative assessment of the patterns of protein production was performed by two-dimensional gel electrophoresis and detection of labeled components by fluorography. Protein and collagen production decreased more than 5-fold as a function of increasing donor age over the age range studied while protein degradation remained unaffected by donor age. The pattern of proteins produced was unaffected by donor age. These data demonstrate a large statistically significant slowdown in general protein synthesis with increasing donor age. This slowdown is not selective, but appears to affect all of the proteins being produced.