Sex hormones and gender differences have been reported to be associated with the occurrences of ventricular arrhythmias. This study investigated the relationship between sex hormones and idiopathic outflow tract ventricular arrhythmias (IOTVA) in adult male patients. Serum sex hormonal levels, which include testosterone, estradiol, and progestogen, were measured by using commercially prepared immunoassay kits. The average count of premature ventricular contractions (PVCs) (number/24h) was assessed by 72h electrocardiographic monitoring. No differences were found in the levels of testosterone and progestogen between the IOTVA male patients and the control males (both P>0.05). However, the level of estradiol in the IOTVA male patients was significantly lower than that in the control males (P<0.05). A significant negative correlation was observed between the number of PVCs and the level of estradiol in the IOTVA male patients (r=0.702, P<0.05). The current study suggested that IOTVA might be associated with the reduction of estradiol level in adult male patients.