The purpose of this investigation was to study the growth and mor-phogenetic potential of the nasal septum cartilage by artificially restricting maxillary growth. This condition, a premature suture synostosis, was achieved by glueing the frontonasal, frontopremaxillary and frontomaxillary sutures at the age of 10 days in 62 Long-Evans/Turku rats. Reactions in the facial frame and the septal cartilage were examined from roentgenograms of dry skulls, photographs of the nasal septum and histological sections of the snout. The snout was turned upwards and reduced in length in the experimental animals by the age of 50 days as compared with the controls. The semi-microscopic photographs of the snout revealed a slight warping of the septum and the histological sections showed a slight lateral slippage of the cartilage from the ethmoidal perpendicular lamina at the age of 25 days. Total slippage had occurred by 50 days. Endochondral ossification was initially disturbed and finally stopped. The warping of the septum and lateral dislocation of the cartilage from the septo-ethmoidal junction seem to support the assumption that the nasal septum cartilage has a morphogenetic potential. The septum alone does not seem to be endowed with any osteo-inductive potential. Interaction between the edge of the cartilage and the bone appears to be essential for endochondral ossification of the septal cartilage.