Abstract.Intact tooth enamel of extracted human teeth was exposed to a pulsed Nd‐YAG laser at an energy density of 10 to 20 joules/cm2.In vitrodemineralization by lactic acid was accomplished by dextran‐producing strains ofStreptococcus mutatisPK‐1 growing on the enamel surface. Scanning electron microscopic observations on the laser irradiated enamel supported micro‐radiographic findings and indicated that the laser irradiated enamel surface was more resistant to decalcification than the non‐irradiated control enamel. Surface changes suggestive of fusion occurred at the low energy density of 10 to 20 joules/cm2. Laser beam irradiation imparted a degree of alteration to enamel surface that subsequently reduced subsurface demineralization. A significant difference in solubility was found between laser irradiated and non‐irradi