The neural cell adhesion molecule (NCAM) is a molecule that mediates calcium-independent cell-cell adhesion, and is expressed during development in a variety of tissues including nonneuronal ones. Expression of NCAM during molar tooth development was analyzed in this present study. In the enamel organ, NCAM expression was detected from the embryonic day 13 onward in restricted areas, including a part of the stratum intermedium of the tooth germ at the bell stage. Mesenchymal cells also expressed NCAM from the bud stage of the first molar onward. In addition to the strong expression in the dental follicle, weak and transient expression was detected in the dental papilla. The second and the third molars appeared to initiate their development by the interaction between the epithelial cells and NCAM-expressing mesenchymal cells. Comparison of the expression patterns of NCAM and transcription factor Barx1 revealed a possibility that Barx1 negatively regulates NCAM expression.