Chondrocytes isolated from auricular cartilage of 1-, 14-, 28- and 56-day-old rabbits were injected intramuscularly as auto- or allogeneic transplants, and the development of the reconstructed cartilage was compared to that of intact tissue. Chondrocytes in cartilage of 1- and 14-day-old rabbits (younger group) were relatively uniform in size. During further development in situ (28 and 56 days) central cells increased considerably and many of them became binucleat-ed. Cartilage reconstructed by chondrocytes from the younger group of animals displayed regular arrangement of cells, i.e. smaller cells at the periphery and larger in the centre. Transplantation of chondrocytes from 28 or 56-day-old rabbits (older group) led to the reconstruction of cartilage with irregular distribution of cells, i.e. some large cells were located at its periphery, while in the centre smaller and larger cells were intermingled in a haphazard manner. Elastic fibres were scanty and thin in cartilage of 1-day-old animals, but their number and size increased with time and they displayed a characteristic pattern. Formation and maturation of these fibres proceeded in cartilage reconstructed by chondrocytes from the younger group of animals similarly as in the intact tissue. Chondrocytes from the older group of rabbits reconstruct -ed cartilage in which the number of elastic fibres was reduced and their arrangement appeared irregular.