Background and Study Aims: Endoscopic Ultrasonography (EUS)is currently indicated for evaluating gastric neoplasm, given its ability to visualize the lining of the stomach and to scan the wall and neighbouring tissues (organs, vessels, lymph nodes). We aimed to value the role of this technique in the diagnosis and staging of primary gastric lymphoma. Patients and Methods:We performed a retrospective study on 37 consecutive patients who had undergone EUS because of clinical suspicion for primary gastric lymphoma. The endoscopic ultrasound system used was Olympus GF-UM 20. Echoendoscopic findings were compared to histologic diagnosis from biopsies. For statistical analysis, the chi-square test was used. Results: Histologic evaluation of the endoscopic bioptic specimens diagnosed gastric lymphoma in 30/37 subjects; conventional biochemical and instrumental procedures excluded secondary disease of the stomach. EUS detected gastric lymphoma in a total of 27 patients, with no false positive results, therefore diagnostic rates were: sensitivity of 90%; specificity of 100%; positive predictability of 100%; negative predictability of 70%; diagnostic accuracy of 92%. All the 27 patients in whom EUS had disclosed lymphoma underwent endosonographic staging: in 25 patients who required medical treatment, EUS staging was compared with histological grading from biopsies, to which it showed a good correlation; in 2 patients who were to be operated on, it could be directly compared with pathologic post-operative examination of the resected speciments,resulting correct in both cases as regard tumor depth of infiltration (T1b), but overstaging 1 case as regards lymph node involvement (N1 on EUS, instead of N0). Conclusions:The diagnosis of gastric lymphoma is based on multiple endoscopic biopsies, with EUS providing a complementary evaluation, particularly helpful in difficult cases; in locoregional staging, on the other hand, endosonography plays a primary role, especially in exploring tumor depth of invasion. Background and Study Aims: Endoscopic Ultrasonography (EUS)is currently indicated for evaluating gastric neoplasm, given its ability to visualize the lining of the stomach and to scan the wall and neighbouring tissues (organs, vessels, lymph nodes). We aimed to value the role of this technique in the diagnosis and staging of primary gastric lymphoma. Patients and Methods:We performed a retrospective study on 37 consecutive patients who had undergone EUS because of clinical suspicion for primary gastric lymphoma. The endoscopic ultrasound system used was Olympus GF-UM 20. Echoendoscopic findings were compared to histologic diagnosis from biopsies. For statistical analysis, the chi-square test was used. Results: Histologic evaluation of the endoscopic bioptic specimens diagnosed gastric lymphoma in 30/37 subjects; conventional biochemical and instrumental procedures excluded secondary disease of the stomach. EUS detected gastric lymphoma in a total of 27 patients, with no false positive results, therefore diagnostic rates were: sensitivity of 90%; specificity of 100%; positive predictability of 100%; negative predictability of 70%; diagnostic accuracy of 92%. All the 27 patients in whom EUS had disclosed lymphoma underwent endosonographic staging: in 25 patients who required medical treatment, EUS staging was compared with histological grading from biopsies, to which it showed a good correlation; in 2 patients who were to be operated on, it could be directly compared with pathologic post-operative examination of the resected speciments,resulting correct in both cases as regard tumor depth of infiltration (T1b), but overstaging 1 case as regards lymph node involvement (N1 on EUS, instead of N0). Conclusions:The diagnosis of gastric lymphoma is based on multiple endoscopic biopsies, with EUS providing a complementary evaluation, particularly helpful in difficult cases; in locoregional staging, on the other hand, endosonography plays a primary role, especially in exploring tumor depth of invasion.