The aim of this in vitro study was to evaluate the influence of food simulating solutions on surface hardness of three different composite resins. A total of 50 specimens were fabricated for each of Filtek Z 250, Clearfil ST, Aelite LS Packable according to the manufacturers' instructions. Ten specimens of each material were randomly selected and stored in 8% ethanol, 50% ethanol, heptane, distilled water, and air at 37°C for 1 week. After one week conditioning period, hardness testing was carried out with a micro hardness tester. The hardness of composite resin materials are strongly influenced by food simulating solutions. © SAGE Publications 2008.