The aim of this study was to evaluate early tensile bond strengths of three commercial resin cements (a dual-cured and two chemically cured) to bovine dentin. Bonding was performed in two environmental conditions, namely room environment (23 degrees C/50% RH) and oral environment (30 degrees C/80% RH). Tensile bond strengths were recorded at 10 minutes, 1 hour, and 1 day after the bonding procedure was completed and were analyzed using one-way ANOVA, Fisher's PLSD test, and Student's t-test. The results showed that bond strengths were statistically greater for all materials (P < 0.05) over time, except for Bistite Resin Cement between 10 minutes and 1 hour (P > 0.05). Variation between the bonding environments was observed only for Bistite Resin Cement at both 10 minutes and 1 hour, and Panavia 21 at 10 minutes. It was concluded that bond strengths were initially weak for the chemically cured materials, and all materials showed significantly greater bond strengths over the first 24 hours, but bonding environment had little influence.