BACKGROUND: Iron deficiency anemia (IDA) is a frequently encountered condition in clinical practice. After conventional endoscopy, the cause of anemia remains unknown in up to 40% of patients. OBJECTIVE: To evaluate prospectively the diagnostic efficacy of a systematic endoscopic approach to IDA and to compare the diagnostic yield of videocapsule endoscopy (VCE) and CT-enteroclysis in endoscopy-negative patients. DESIGN: Consecutive patients with IDA were enrolled prospectively. SETTING: Open-access endoscopy within an academic hospital. PATIENTS: This study involved 189 patients with IDA, including 98 women and 91 men; mean (+/-standard deviation) age 68 years+/-16.6 years. INTERVENTION: Patients with IDA underwent gastroscopy and colonoscopy plus ileoscopy. Endoscopy-negative patients were further blindly evaluated by both CT-enteroclysis and VCE. MAIN OUTCOME MEASUREMENTS: Diagnostic yield of conventional endoscopy; diagnostic yield of VCE versus CT-enteroclysis. RESULTS: Endoscopy results were positive in 144 of 189 patients (76.2%). CT-enteroclysis and VCE allowed a diagnosis in 37 of 45 endoscopy-negative patients (82.2%). Overall, VCE was superior to CT-enteroclysis (77.8% vs 22.2%; P<.001), in particular when flat lesions were found. LIMITATIONS: Single-center study. CONCLUSION: A systematic approach to IDA, which includes standard endoscopy, VCE, and CT-enteroclysis allows an overall diagnostic rate of 95.7%; however, CT-enteroclysis should be limited to cases of nondiagnostic VCE.