Free grafts of connective tissue, without epithelium, were transplanted from either the keratinized gingiva or the non-keratinized alveolar mucosa (controls) into areas of the alveolar mucosa in seven monkeys. The grafts were placed in pouches created in the connective tissue as close as possible to the overlying epithelium. After 3-4 weeks, the transplants were exposed by removal of the overlying tissue in order to allow epithelialization from the surrounding non-keratinized alveolar mucosa. The transplants were examined clinically and histologically at time peiods between 1 and 12 months. The gingival connective tissue grafts became covered with keratinized epithelium displaying the same characteristics as those of normal gingival epithelium. The alveolar mucosa transplants were covered with non-keratinized epithelium. This indicated that gingival connective tissue is capable of inducing the formation of a keratinized gingival epithelium.