["To assess the effect of ultrasound operators' confidence in diagnosis of ovarian cancer, and the factors influencing diagnostic accuracy.", 'Ultrasound images of selected ovarian cancers and controls were evaluated by 8 sinologists who were instructed to diagnose and classify lesions into benign, borderline or malignant, and we use structured questionnaire to investigate the level of confidence. We analyzed the accuracy of diagnosis, including sensitivity, specificity, positive and negative likelihood ratios and accuracy depending on the different levels of confidence. In addition, factors influencing diagnostic accuracy was assessed by logistic regression analysis.', 'A total of 426 cases were examined. The confidence score was significantly increased with the level of accuracy (test for trend, p<0.05). Borderline tumors were most difficult to diagnose, and had lower accuracy, sensitivity and specificity compared with benign and primary invasive tumors. Working experience was positively closely associated with diagnosis accuracy. Logistic regression analysis revealed working experience and confidence score to be positively related to the diagnostic accuracy(OR, 95%CI, 1.68, 1.15-3.97 for working experience; OR, 95%CI, 3.75, 1.67-6.98 for confidence score).'] Does ultrasound operators ' confidence influence diagnosis of ovarian tumors - a study in China?