INTRODUCTION: Nocturnal penile tumescence and rigidity (NPTR, or, more simply, NPT) studies, with or without the help of a recording computer (Rigiscan), have been traditionally positioned at the head of several erectile dysfunction (ED) diagnostic flowcharts with the aim to distinguish between psychogenic and organic etiology. Shall we continue to consider these tools as a diagnostic gold standard in ED diagnosis?METHODS: Four scientists with expertise and/or interest in the area of ED pathophysiology and diagnosis were asked to contribute their opinions.MAIN OUTCOME MEASURE: To give to The Journal of Sexual Medicine's reader new stimuli to reexamine a still largely utilized tool utilized in sexual medicine's clinical practice.RESULTS: Of the four experts discussing the topic, the first who is the section editor of the Controversy section, believes that NPT/Rigiscan cannot be considered a useful diagnostic tool for differential diagnosis in ED. He is supported by the physiological considerations of the second expert and by the experimental evidence produced and discussed by the expert number four who questions the accuracy, reliability, and usefulness of these tools to measure a critical aspect of the erection physiology which is the adequate rigidity. In contrast, with several good arguments, the third expert still suggests the use of these tools, perhaps not for every man presenting with ED, but at least for the patient with no neurovascular risk factors who presents with a history suggestive of a psychogenic cause.CONCLUSION: The reader will judge if the expensive, complicated, and time-consuming effort to record nocturnal erectile activity is or is not useful anymore for the patient and for orienting the treatment choices.