To assess the diagnostic value of upper intestinal fiber endoscopy in primary small intestinal lymphomas observed in an underdeveloped Mediterranean country, the endoscopic records of 40 patients (Group A) offering histologic evidence of lymphoma were compared with those of 80 patients (Group B) displaying clinical findings of small intestinal disease, but who eventually proved to be free of lymphoma after a complete work-up. The endoscopic procedure reached the jejunum in 91% cases and was well tolerated with only one reversible complication. Five primary endoscopic patterns could be defined, occuring either alone or in various combinations. The infiltrated pattern was the most sensitive (0.80) and specific (0.96) finding with predictive positive and negative values reaching 0.88 and 0.93, followed by the nodular pattern (sensitivity 0.60, specificity 0.84). Other primary lesions (ulcerations, mosaic pattern, mucosal fold thickening dlone) were either nonsensitive or nonspecific or both. The infiltrated pattern proved to be more valuable than any association of primary lesion. Per endoscopic biopsies were diagnostic of lymphoma in 85% cases. These findings strongly suggest that upper intestinal fiber endoscopy, using long ending view instruments should be the first investigation in patients suspected of small intestinal lymphoma in developing Mediterranean countries.