Fifty-one colon neoplasms larger than 1 cm were diagnosed by double-contrast barium enema (DC), but were not confirmed by initial endoscopy. Seventeen lesions were shown to be radiographic false-positive diagnoses by careful review of the original radiographs (10 cases) or repeat DC (7 cases). The presence of a neoplasm was confirmed in 21 cases (41%) by repeat endoscopy or surgery (15 cases) or by repeat DC alone (6 cases). Seven (47%) of 15 resected lesions were malignant. The results emphasize the complementary nature of the DC and endoscopy in detection of colon neoplasms. When discrepancies between the radiographic and endoscopic diagnoses cannot be explained by careful review of the DC, repeat radiographic or endoscopic examination should be performed. © Lippincott-Raven Publishers.