Objective       To evaluate the diagnostic value of ultrasonography for neonatal necrotizing enterocolitis (NEC).       Methods       Clinical data of 65 cases (at an age from 3 h to 30 d) diagnosed as NEC in our hospital from January 2010 to October 2011 were collected in this study. Findings of ultrasonography was analyzed and compared with those of X-ray plain film.       Results       Ultrasonography displayed that there were multiple bowel wall thickening observed with in 52 cases (80.0%)

mainly in small intestine (with average thickness over 3 mm) and accompanying with seroperitoneum. Intestinal wall pneumatosis were found in 41 cases. Echogenic dots or granular gas echogenicities were found under bowel mucosa in 32 cases (49.2%)

linear or bar-like hyperecho was found under the serosa in 9 cases (13.8%). There were 15 cases with portal vein pneumatosis observed with ultrasonography

with bubble or beadlike hyperecho in the main truck or branches of portal vein

and/or spot or striped hyperechoic area in portal vein branches in the liver parenchyma. Ultrasonography had a higher positive rate to intestinal wall pneumatosis than X-ray plain film（P0.05）.       Conclusion       Ultrasonography play an important role in early diagnosis and follow-up monitoring for NEC.