Abstract: Objective To compare the accuracy and reliability between contrast-enhanced ultrasound （CEUS） and conventional ultrasound in diagnosis of <3cm liver metastases，and to discuss the role of CEUS in diagnosis of small liver metastases. Methods Eighty-seven patients with known malignancies and suspicious liver metastases were performed CEUS. The perfusion patterns of liver metastasis were evaluated and thegraduation of score for the differential diagnosis between malignant and benign tumor were conducted before and after CEUS. Results Thescoresin 21 metastases (24.1%) evaluatedby CEUSwerehigher2~4thanthatby conventional ultrasound,and 21 metastases (24.1%) higher 1.In 33 patients (37.90%), moremetastases wereobservedby CEUSthan byconventionalultrasound. There was significant difference in accuracy between CEUS and conventional ultrasound indiagnosis of small liver metastases (P<0.01). Conclusion CEUS had unique advantage in qualitative diagnosis of small liver metastases. It improved sensitivity in detection of small hepatic metastases, which is useful for staging andselecting treatment protocols in patients with extra-hepatic original malignancies.