Objective To analyse the misdiagnosed reasons in 176 cases of ovarian mass by ultrasound . Methods Ultrasound misdiag-nosed features in 176 cases of ovarian mass were analyzed retrospectively. According to the results from their operation and pathology the misdiagnosed reasons of ovarian mass by ultrasound were discussed. Misdiagnosis happened in medical history and possible etiology. Conclusion Ultrasound examination and diagnosis of ovarian mass should be closely combined with clinical information to reduce mis-diagnosed cases .