AIM:To analyze the radiological features of multiple primary carcinoma (MPC) in the upper gastrointestinal (GI) tract,study its biological characteristics and evaluate X-ray examination in its diagnosis. METHODS:Hypotonic double-contrast GI radiography was performed in 59 multiple primary carcinoma cases,pathologically proved by surgery or endoscopy biopsy. Radiological findings were analyzed. RESULTS:Of the 59 cases,esophageal MPC (EMPC) was seen in 24,esophageal and gastric MPC (EGMPC) in 27 and gastric MPC (GMPC) in 8. Of the 49 lesions found in 24 EMPC,hyperplastic type was seen in 23,medullary type in 9. The lesions were located at the upper (n = 17),middle (n = 19) or lower (n = 13) segment of the esophagus. In 27 EGMPC,the esophageal lesions were located at the middle (n = 16) or lower (n = 11) segment of the esophagus,while the gastric le-sions were located at the gastric cardia (n = 16),fundus (n = 1),body (n = 3) and antrum (n = 7). The esophageal lesions were mainly of the hyperplastic type (n = 12) or medullary type (n = 7),while the gastric lesions were mainly of the hyperplastic type (n = 18). A total of 119 lesions in the 59 patients with synchronous multiple carcinoma were proved by surgery or endoscopy biopsy,and preoperative upper radiographic examination detected 100 of them (84.03% sensitivity). Eighteen (52.94%) of the T1 lesions were found during preoperative diagnosis by radiographic examination. Moreover,only 3 (3.53%) of the T2-4 lesions were misdiagnosed. CONCLUSION:Hypotonic double-contrast upper gastrointestinal examination,providing accurate information about lesion morphology,location and size,can serve as a sensitive technique for the preoperative diagnosis of MPC. AIM: To analyze the radiological features of multiple primary carcinoma (MPC) in the upper gastrointestinal (GI) tract, study its biological characteristics and evaluate X-ray examination in its diagnosis. METHODS: Hypotonic double-contrast GI radiography was performed in 59 multiple Primary cancer cases, pathologically proven by surgery or endoscopy biopsy. Radiological findings were analyzed. Of the 59 cases, esophageal MPC (EMPC) was seen in 24, esophageal and gastric MPC (EGMPC) in 27 and gastric MPC 8. Of the 49 lesions found in 24 EMPC, hyperplastic type was seen in 23, medullary type in 9. The lesions were located at the upper (n = 17), middle (n = 19) or lower (n = 13) segments of the esophagus. In 27 EGMPC, the esophageal lesions were located at the middle (n = 16) or lower (n = 11) segment of the esophagus, while the gastric le- sions were located at the gastric cardia (n = 16) , fundus (n = 1), body (n = 3) and antrum (n = 7). The esophageal lesions were mainly of the h While the gastric lesions were mainly of the hyperplastic type (n = 18). A total of 119 lesions in the 59 patients with synchronous multiple carcinoma were proved by surgery or Eighteen (52.94%) of the T1 lesions were found during preoperative diagnosis by radiographic examination. Moreover, only 3 (3.53%) of the T2-4 lesions (84.03% sensitivity) CONCLUSION: Hypotonic double-contrast upper gastrointestinal examination, providing accurate information about lesion morphology, location and size, can serve as a sensitive technique for the preoperative diagnosis of MPC.