Objectives To study the influence of insulin on IGF-Ⅰ and IGFBP-Ⅰ secretion of the hum an endometrial stromal cells. Methods Late proliferative phase endometrial stromal cells were isolated from endometriu m tissues and then cultured for 24 h in Hams F-12 only as a control and in Hams F-12 with different concentrations of estradiol (E2) and insulin (INS) as trea ted groups. Simultaneously, the endometrial stromal cells from late secretory phase endometrium were cultured for 24 h in Hams F-12 only as a control and in Hams F-12 supplemented with different concentrations of progesterone (P) and i nsulin as treated groups. After 24 h of culturing, the mediums were collected f or either IGF-Ⅰ or IGFBP-Ⅰ assays.Result The concentrations of IGF-Ⅰ in medium from cultured endometrial stromal cells i n the proliferative phase were 0.78±0.47 ng/ml in the hormone-free control group; 1.44±0.59 ng/ml and 1.39±0.33 ng/ml in 100 pg/ml E2 group and 20 μU /ml INS group, which was higher than that of the control group (P<0.05 and P<0.01, respectively). The IGF-Ⅰ concentration in the 100 μU/ml INS group was 2.03±0.53 ng/ml, which was higher than that of the 20 μU/ml INS group (P<0.01). Levels of IGF-Ⅰ in the 100 pg/ml E2 plus 20 μU/ml INS gro up was 2 .18±0.36 ng/ml, which was significantly higher than that of the 20 μU/ml INS and 100 pg/ml E2 group (P<0.01), but lower than that of the 100 pg/ml E2 p lus 100 μU/ml INS group (3.42±0.75 ng/ml), P<0.01. The concentration o f IGFBP-Ⅰ in medium from cultured endometrial stromal cells in the secretory ph a se was 2.50±1.39 ng/ml in the hormone-free control group and 5.44±2.09 ng /ml in the 10 pg/ml P group, which was significantly higher than that of the con trol (P<0.01). IGFBP-Ⅰ concentration in 20 μU/ml INS group was 0.1 6±0 .58 ng/ml, which was lower compared with control, but higher compared with the 100 μU/ml INS group (P<0.01). The level of IGFBP-Ⅰ in the 10 ng/ml P plu s 20 μU/ml INS group was 2.10±1.17 ng/ml, lower compared with the 10 ng/ml P gr oup, but higher compared with the 10 pg/ml P plus 100 μU/ml INS group, P<0 .01. Conclusions Insulin can stimulate basal (without hormone) and E2-stimulated IGF-Ⅰ secreti on in cultured stromal cells from human late proliferative endometrium in adose -dependent manner. Insulin can suppress basal (without hormone) and P-stimula ted IGFBP-Ⅰ secretions in cultured stromal cells from human secretory endomet rium in a dose-dependent manner.