The abilities of embryonic and adult rat sensory neurons to regenerate were compared when cultured on cryostat sections of normal and lesioned sciatic nerve tissues. Differences in neurite growth, visualized by GAP-43 immunolabelling, were most pronounced on substrata consisting of longitudinal sections of normal versus predegenerated sciatic nerve. Adult dorsal root ganglion (DRG) neurons grew only on the lesioned nerves. Neurites extended along these sections in a characteristically longitudinal orientation, and this growth was not dependent on nerve growth factor. Embryonic DRG neurons extended neurites on sections from both types of nerves. These results highlight important differences in the regenerative abilities of embryonic and adult DRG neurons when grown on physiologically appropriate substrata.