The adhesion to acid-etched enamel of a four-component composite, Concise Enamel Bond System, was studied. The composite was applied undiluted over an intermediate resin layer and diluted with different amounts of resin. Corresponding surfaces of contralateral premolars were used to ensure that the composite samples were tested on areas with similar enamel etch patterns. Eighty specimens were tested. The results of this study indicated that the adherence of undiluted composite to etched enamel surfaces was not improved by using an intermediate layer of low-viscous resin. Composite diluted with liquid resin had poorer adherence than undiluted composite. There was no difference in the results from two degrees of dilution.