Objectives. The purpose of this study was to investigate the effect of temperature on the flexural behavior for four visible light-cured hybrid composite materials. Methods. Light-cured samples were post-cured for 24 h at 37°C in 100% relative humidity prior to testing. Flexural tests were performed at the following water immersion temperatures: 5, 15, 25, 37, 45 and 55° C, as well as in the dry condition which served as control. The following flexural property parameters were obtained as a function of test temperature: flexural strength, σ fs, flexural modulus, E fs, flexural stress at 0.06% total offset strain, σ 0.06% (yield stress), and the total displacement at fracture, δ fs . Statistically significant differences (p<0.01) in flexural parameters were noted for all the materials as a function of test temperature. Results. The yield stress, σ 0.06% was found to be most sensitive to thermomechanical changes. The results of this study indicate significant softening due to temperature under wet immersion test conditions for all materials. The temperature range at which two of the materials show significant reduction in yield stress compare well with “Wet T g” values obtained by dynamic thermal mechanical analysis (Culbertson et al., 1990; 1991). Significance. The effect of damage accumulation on surface or subsurface microstructure due to transient thermomechanical loads needs to be taken into account in the correlation of in vitro and in vivo wear or creep behavior.