To investigate the proliferative ef fect of keratinocyte growth factor (KGF 2) on human adult keratinocytes. Methods: The standard medium was keratinocyte growth medium wit hout bovine pituitary extract (BPE), hydrocortisone or epidermal growth factor ( EGF). Keratinocytes from a 48 year old subject were cultured and seeded on dis hes with standard medium of EGF in cell density of 2×10 4/32 mm 2. After 24 hours, the medium was replaced by the standard medium with 0, 4, 16, 125 and 50 0 ng/ml KGF 2, respectively. The standard medium with EGF was used as the posit ive control and the standard medium without EGF or KGF 2 was used as the negati ve controls. The growth of keratinocytes was monitored by 3 (4,5 dimethythiazo l 2 yl) 2,5 dipheyl tetrazolium bromide (MTT) assay and by photographs on day s 3, 5 and 7, respectively. Results: KGF 2 in concentrations of 4 500 ng/ml showed a sign ificant proliferative effect on days 5 and 7 as compared with that of the negati ve controls (P< 0.01 ). On day 3 the cells were prolifer ated to 1.5 2.5 fold, on day 5 to 3 5 fold and on day 7 to 3 12 fo ld in KGF 2 medium as that of the negative controls. The optimal response occur red when the concentration of KGF 2 was 125 ng/ml on day 7. Cell proliferation was also consistently higher in all KGF 2 concentrations as compared with that of the positive controls. Conclusions: KGF 2 has significant effects on the proliferatio n of adult keratinocytes, which are more effective than that of EGF. This study supports KGF 2 can improve the healing of chronic wounds in adults in clinic. To investigate the proliferative ef fect of keratinocyte growth factor (KGF 2) on human adult keratinocytes. Methods: The standard medium was keratinocyte growth medium wit hout bovine pituitary extract (BPE), hydrocortisone or epidermal growth factor (EGF). Keratinocytes from a 48 year old subject were cultured and seeded on dis hes with standard medium of EGF in cell density of 2 × 10 4/32 mm 2. After 24 hours, the medium was replaced by the standard medium with 0, 4, 16, 125 and 50 0 ng / ml KGF 2, respectively. The standard medium with EGF was used as the posit ive control and the standard medium without EGF or KGF 2 was used as the negati ve controls. The growth of keratinocytes was monitored by 3 (4,5 dimethythiazo l 2 yl) 2,5 dipheyl tetrazolium bromide (MTT) assay and by photographs on day 3, 5 and 7, respectively. Results: KGF 2 in concentrations of 4 500 ng / ml showed a significant proliferative effect on days 5 and 7 as compared with that of the negati ve controls (P <0.01). On day 3 the cells were prolifer ated to 1.5 2.5 fold, on day 5 to 3 5 fold and on day 7 to 3 12 fo ld in KGF 2 medium as that of the negative controls. The optimal response occur red when the concentration of KGF 2 was 125 ng / ml on day 7. Cell proliferation was also consistently higher in all KGF 2 concentrations as compared with that of the positive controls. Conclusions: KGF 2 has significant effects on the proliferatio n of which keratinocytes, which are more effective than that of EGF. This study supports KGF 2 can improve the healing of chronic wounds in adults in clinic.