Methylene blue and silver impregnation techniques were used to study the morphological features of sensory nerve terminations in selected regions of the oral mucosa from human subjects and a number of animals. Sensory nerve endings vary widely in their morphology and consist of free or organized terminations. Organized terminations can be classified as being of a simple, complex or compound coiled type. Nerve terminations differ sufficiently in histological detail to prevent their accurate correlation with specific sensations. Consequently the theory of sensibility which is favoured suggests that sensation is a function of the pattern of responses of nerve fibres reaching higher centres.