OBJECTIVE To observe the effect of the expression of proliferating cell nuclear antigen (PCNA) induced by basic fibroblast growth factor (bFGF) on the proliferation of bovine lens epithelial cells (BLECs). METHODS The second passage BLECs were cultured with different concentrations of bFGF (0.01 - 100.00 microgram/L) for 24 - 96 hours, the DNA synthesis of BLEC was measured by (3)H-TdR incorporation, and the expression of PCNA and the cell cycle were counted by the flow cytometer. RESULTS bFGF promoted the proliferation of BLEC with concentration and time dependent manner. The (3)H-TdR incorporation of BLEC was increased to 11 772.5 and 10 988.2 respectively much higher than the control group (6 550.5). The addition of bFGF 10.00 microgram/L for 24 - 48 hours up-regulated the expression of PCNA (77.40%), and caused the BLEC population to increase in S phase (23.41%) and G(2)/M phase (20.76%). Comparing with the control group, there was significant difference (P < 0.05). CONCLUSION bFGF stimulateds the proliferation of BLEC by up-regulating the expression of PCNA and changing the cell cycle.