Objective To evaluate the diagnostic value of combining real-time three-dimensional ultrasonography with three-dimensional power Doppler ultrasound for the patients with small ovarian masses.Methods One hundred and seven patients with small ovarian masses were examined with real-time three-dimensional ultrasonography and three-dimensional power Doppler ultrasound.The images and the relationship between benign and malignant small ovarian masses were analyzed.Results Benign and malignant small ovarian tumors had statistical differences in these three parameters:the envelope,inner wall and whether there being central vessels.The sensitivity and specificity of combining real-time threedimensional ultrasonography with three-dimensional power Doppler ultrasound to diagnose malignant small ovarian tumors were 92.9% and 97.3% respectively.Conclusions Combining real-time three-dimensional ultrasonography with three-dimensional color Doppler energy can be used to diagnose the small ovarian masses and provide valuable information to identify malignant ovarian tumors.A small ovarian tumor with incomplete envelope,irregular inner wall and there being central vessels indicated the possibility of being malignant.