In order to investigate the effect of TGF beta 1 gene transfer on the biological characteristics, the effects of gene transfer and supernatant of transfected osteoblasts on the proliferation and ALP activity of osteoblasts were detected by 3H-TdR and MTT. Our results showed that TGF beta 1 gene transfer had no effect on the biological characteristics and the activated supernatant of transfected osteoblasts stimulated proliferation and inhibited ALP activity of osteoblasts. TGF beta 1 gene transfer could promote the expression of TGF beta 1 and the biological characteristics of transfected osteoblasts were stable, which might be helpful for gene therapy of bone defects in vivo.