Abstract: Objective To explore the effects of proliferation and apoptosis on human keratinocytes with yttrium chloride(YCl₃) under serum-free cultures.Methods The proliferation of human epidermal kerat inocytes was detected by MTT method.Tunel method was used to measure the apoptosis rates after ultraviolet radiation.Results Compared with control group,the proliferation of human kerationcytes showed no significant difference at the lower concentration(<1.0mmol/L) of YCl₃(P>0.05),but a apparent growth suppresstion at more than 2.0mmol/L of YCl₃(P<0.01).At 0.1mmol/L of YCl₃,keratinocytic apoptosis induced by ultraviolet was more significant suppression than the control group(P<0.05),but in the other groups(>0.5mmol/L) of YCl₃,the apoptosis showed no difference compared with control group(P >0.05).Conclusion Low concentration of YCl₃ had no apparent bad effects on the proliferation of human keratinocytes,and may partly protecthuman keratinocytes from the apoptosis induced by ultraviolet.