An in vitro study was undertaken to evaluate the ability of a dentin-enamel bonding system to bond to wet, as well as to dry, dentinal substrate. The All-Etch/All-Bond system was used to bond to wet and dry dentin using 10% and 37% phosphoric acid surface conditioning. The wet dentinal surfaces exhibited significantly higher bond strengths than did the dry surfaces. It is suggested that, because of the unique behavior of the resin-primer mixture, the dentinal surface is adapted to much more thoroughly and intimately when the surface is wet.