We prospectively evaluated the diagnostic yield of push enteroscopy using either the Olympus SIF 10-LY fiberscope or the SIF-100 video enteroscope in 120 patients suspected of having small-bowel pathology. Insertion beyond the ligament of Treitz, checked by fluoroscopy, ranged from 30 to 150 cm (median 100). The source of bleeding was identified in 25 (41%) of 61 patients referred for gastrointestinal bleeding of obscure origin; vascular malformations were the most common finding, followed by neoplasias. Of 16 patients with inherited polyposis syndromes, multiple distal duodenal or jejunal hamartomas were diagnosed in five of six with Peutz-Jeghers syndrome and multiple duodenal or jejunal adenomas in six of 10 with familial adenomatous polyposis. Overall, isolated vascular malformations were successfully cauterized in three patients, and polypectomy was performed in 12 patients. Endoscopic and histological alterations, in both duodenum and jejunum, were found in 16 of 43 patients with diarrhea and/or malabsorption of unclear origin. The remaining 27 had normal duodenal and jejunal mucosal appearances; six had abnormal histological findings only in the jejunum and one both in the duodenum and in the jejunum. If we take jejunal histology as diagnostic, the sensitivity of duodenal histology was 74% and the specificity was 100%. We conclude that push enteroscopy provides useful diagnostic information and has therapeutic capabilities in patients with small-bowel pathology.