The purpose of this study was to evaluate the effects of 2 new acid-etching solutions, nonrinse conditioner (NRC) and 17% ethylenediaminetetraacetic acid (EDTA), on enamel surface morphology, and to compare the new solutions with traditional 37% phosphoric acid. The effect of prolonged etching time was also investigated. The buccal surfaces of 80 extracted third molars were etched with one of the 3 acids for 15, 30, or 60 seconds. The central regions of the specimens were examined with a scanning electron microscope. Shorter etching time with phosphoric acid resulted in a relatively smooth enamel surface compared with longer treatments. Irrespective of treatment time, NRC produced an aprismatic etch pattern, which suggested a potentially retentive morphological character. EDTA treatment had the least effect of all etchants tested.