The purpose of this study is to assess possibilities of ultrasonic tomography (UST) in the diagnosis of delineated liquid clusters in the patients operated on for stomach cancer. In the study there were analyzed data of 1500 patients operated on for stomach cancer in N.N.BIokhin Russian Cancer Research Center of RAMS for the period from 1998 to 2006. In 221 patients (14.7 %) there were suspected post-operative complications in clinical and laboratory data. 54 patients (3.6 %) were diagnosed with post-operative complications. The latter constituted the main group in our study. Fluid accumulation in the abdominal cavity is formed with equal frequency in all variants of surgical intervention in patients, operated on for stomach cancer. In the diagnosis of abscesses and hematomas UST is characterized by high sensitivity, however, specificity and accuracy of this method does not reach the desired values. The effectiveness of UST and X-ray computed tomography are comparable, X-ray diagnostics has low indicators of sensitivity.