To obtain information on correlated growth of the maxillary base and dental arch in submucous mid-palatal clefts, such clefts were surgically created in 18 domestic cats. The growth ratios of the dento-maxillary complex were then compared with corresponding parameters in 18 unoperated controls. When fully grown, the operated cats had developed a significant hypoplasia of the maxillary base. Also the upper dental arch in these cats showed a slight reduction in width, but significantly so only in the posterior region. The results obtained seemed to demonstrate a mutual dependence in growth of these two parts of the dento-maxillary complex, but to a limited degree. Whereas the maxillary base was significantly influenced by the altered morphology in the mid-palatal area, the dental arch growth and its final dimension seemed to be more responsive to compensatory mechanisms.