Abstract: Objective To investigate the relation of peripheral blood estradiol,progesterone and testosterone levels with irritable bowel syndrome(IBS).Methods Forty-eight patients with IBS identified according to Rome Ⅱ diagnostic criteria and 30 healthy subjects as controls were analyzed for peripheral blood sex hormone levels by radioimmunossay and corresponding software.Results In male patients with IBS,blood testosterone level was significantly lower than that of the control group(P<0.05),but blood estradiol and progesterone showed no significant differences between the two groups(P>0.05).In the female patients,blood estradiol level was significantly lower than that of the control group(P<0.05),whereas blood progesterone and testosterone levels had no significant differences between the two groups(P>0.05).Conclusion Peripheral blood testosterone level in male IBS patients and estradiol level in female patients are lower than those of healthy subjects,suggesting that IBS might be associated with blood sex hormone disorder.