OBJECTIVE To investigate the effect of linear polarized infrared light irradiation on the proliferation of primary cultured rabbit articular chondrocytes irradiation. METHODS Primary cultured rabbit articular chondrocytes were irradiated with linear polarized infrared light irradiation (Super Lizer) at the power intensity of 20% (360 mW) to 100% (1800 mW) for 5 min per day for 5 days, and CCK-8 assay was used to measure the proliferative activity of the chondrocytes after the exposures. RESULTS The D(450) values of the cells irradiated at the power intensity of 60% (1080 mW) and 80% (1440 mW) (1.88∓0.11 and 1.99∓0.05, respectively) were significantly greater than that of the control cells (0.95∓0.38, P<0.05). The irradiation with Super Lizer at lower (20%, 360 mW and 40%, 720 mW) or higher (100%, 1800 mW) power intensities did not cause significant increases of the D(450) values. Compared with the control group, Super Lizer irradiation at the power intensities of 20%, 40%, 60%, and 80% resulted in increment ratios of chondrocyte viability of (48.75∓15.4 )%, (67.02∓29.61)%, (97.93∓11.57)%, and (108.52∓5.81)%, respectively, but at 100% power intensity (1800 mW), the irradiation caused a lowered chondrocyte viability increment ratio of (62.84∓31.12)%. CONCLUSIONS Linear polarized infrared light irradiation can promote the proliferation of chondrocytes in an intensity-dependent manner, and the strongest effect occurs with the irradiation power intensity of 80% (1440 mW).