Abstract： Objective To compare the diagnostic values of US-guided optical imaging system (OPTIMUS) and full-field digital mammography (FFDM) in breast neoplasms. Methods Sixty-four patients suspected of breast neoplasms underwent OPTIMUS and FFDM before surgery. All patients were proved histopathologically. The accuracy of diagnosis was compared with chi-square test. Results Sixty-five masses were delineated by OPTIMUS and FFDM. The diagnostic accuracy, sensitivity and specificity of OPTIMUS were 86. 2% ( 56/65 ), 87.0% ( 20/23 ) and 85.7% ( 36/42 ), respectively. The positive likelihood ratio was 6. 09 and the negative likelihood ratio was 0. 175. The diagnostic accuracy, sensitivity and specificity of FFDM were 73.8% (48/65), 82. 6% ( 19/23 ) and 71.4% (30/42), respectively. The positive likelihood ratio was 2. 892 and the negative likelihood ratio was 0. 243. There were no significant differences between OPTIMUS and FFDM ( x2 = 3. 077 ,P ＞ 0. 05). Conclusion OPTIMUS is similar and supplementary to FFDM for the diagnosis of breast neoplasms.