Five current dentin adhesives were evaluated for their ability to bond to caries-affected dentin. The materials were: total etch [Solid Bond (SB)], two self-etch [Clearfil SE Bond (CSE), Etch and Prime (EP)], two one bottle [Prime and Bond 2.1 (PB), One Coat Bond (OCB)]. Sixty extracted molar teeth with proximal caries (mesial or distal) extending into mid-dentin were used. By grinding normal and caries-affected proximal surfaces, flat dentin surfaces were obtained. The surfaces were then bonded with each adhesive system and composite resins were added to the surfaces by packing the material into a cylindrical-shaped plastic matrix with an internal diameter of 2.5 mm and height of 3 mm. Shear bond testing was performed following 10 days incubation of specimens in distilled water at 37°C. Results were analysed by Kruskal-Wallis ANOVA, and Mann-Whitney U multiple comparison test and Wilcoxon rank tests. The results obtained with CSE, SB, and EP were similar in caries affected and normal dentin (P > 0.05). But bonds made to normal dentin with OCB and PB were lower (P < 0.05) than bonds to caries-affected dentin. Bonding to caries-affected dentin with CSE (24.49 ± 5.38), SB (21.49 ± 9.15), and EP (21.19 ± 9.17) showed shear bond strengths higher than OCB (17.43 ± 9.78) and PB (14.10 ± 7.94) (P < 0.05). Bonding to normal dentin with CSE (29.91 ± 8.95) was the highest (P < 0.05). SB (21.17 ± 5.41) and EP (17.45 ± 6.21) showed shear bond strengths higher than OCB (11.99 ± 10.15) and PB (10.57 ± 4.56) (P < 0.05). © 2002 Blackwell Science Ltd.