This study sought to evaluate the long-term bond strength of etch-and-rinse and self-etch adhesive systems to dentin after one year of water storage. Crown fragments from the buccal surface of extracted bovine incisors were ground flat to expose dentin surfaces. Four etch-and-rinse and two self-etch bonding agents were used according to manufacturers' instructions. Bonded specimens were stored in water for either 24 hours or one year at 37 delete C. After elapsed storage times, specimens were tested for shear bond strength (SBS) at 0.5 mm/min. Data were analyzed by ANOVA and Tukey's tests (p < 0.05). Both evaluated factors (adhesive system and storage time) and their interactions were statistically significant. Single Bond produced the highest SBS regardless of the water degradation period. One-year water storage reduced the SBS of Prime & Bond NT and One-Up Bond F significantly; the other adhesives performed similarly. Long-term bond strengths of etch-and-rinse and self-etch adhesive systems are susceptible to hygroscopic and hydrolytic effects to varying extents, depending on their chemistry and structure. The presence of monomers with different properties might induce preferential degradation of specific adhesive polymer systems.