BACKGROUND Accurate knowledge of tumour presence and location is essential to treat neuroendocrine tumours (NETs). Standard imaging has been hampered by low sensitivity and lack of spatial resolution. This study assessed prospectively the diagnostic value and impact of combined 6-[18F]fluorodihydroxyphenylalanine positron emission tomography-computed tomography (18F-DOPA-PET/CT) in the management of NET. METHODS 18F-DOPA-PET/CT findings in 61 patients with suspected NET were compared with a composite reference standard including somatostatin receptor scintigraphy (SRS), magnetic resonance imaging, computed tomography, histological examination and clinical follow-up. The impact on clinical management was estimated by calculating the proportion of patients whose treatment changed as a result of 18F-DOPA-PET/CT findings. RESULTS 18F-DOPA-PET/CT correctly identified 32 of 36 patients with NET. The sensitivity and specificity of 18F-DOPA-PET/CT for the detection of NET were 91 and 96 per cent respectively. Sensitivity using SRS was significantly lower (59 per cent), whereas the specificity was similar (86 per cent). In 16 (26 per cent) of the 61 patients the management was altered as a result of new findings on 18F-DOPA-PET/CT. CONCLUSION 18F-DOPA-PET/CT yields a high sensitivity and specificity in the detection of NET. The clinical impact was highly relevant as changes in therapy were observed in more than a quarter of the patients.