A study was undertaken to assess the diagnostic accuracy of contrast-enhanced MR mammography (MRM) of the contralateral breast in patients treated by breast-conserving therapy previously. A total of 119 patients underwent 145 standardized dynamic MR studies (1 T, T1-weighted 3D FLASH, 0.2 mmol Gd-DTPA/kg body weight). We retrospectively evaluated the results of conventional methods and MRM. A total of 11 contralateral carcinomas were present (detection rate 9%). The interval between treatment of the first primary and identification of contralateral malignancy was 9-80 months (mean 33 months). The MRM allowed detection of four otherwise occult malignancies. One of 11 cancer was missed on MRM due to benign appearance of enhancement. Compared with conventional methods MRM improved sensitivity (91 vs 64%) and specificity (90 vs 84%), respectively. This study suggests that additional MRM of the contralateral breast increases the diagnostic accuracy not only by enhancing the detection of second cancers but also by reducing false-positive results.