Pudenal somatosensory evoked potential (PSEP) and bulbocavernosus reflex (BCR) testing have been reported to be useful in the evaluation of erectile dysfunction and neurogenic bladder. 461 patients with sexual dysfunction were studied to determine the usefulness of the above tests. Abnormality of PSEP was found significantly in upper motor neuron (UMN) type spinal cord patients and average prolonged P1 latency was 47.4 +/- 9.8 msec. Lower motor neuron (LMN) type spinal cord patients revealed great abnormality in BCR latency with an average value of 44.9 +/- 14.5 msec on the right and 44.2 +/- 15.6 msec on the left. Additionally significant differences were obtained in patients with diabetes mellitus, pelvic trauma and spinal cord lesion of the UMN type in the study of PSEP. There was also a significant difference in the patients with diabetes mellitus, pelvic trauma and spinal cord lesion of the LMN type in the BCR study. The findings of our study suggest that PSEP together with BCR study is useful in assessing the integrity of the sacral reflex arc and the central afferent pathway, in differentiating the lesion site and in providing basic data for the management plan in sexual rehabilitation. Furthermore, because erection is under the influence of both the somatic and autonomic nervous system, BCR study and PSEP combined with currently studied electrical activity of the corpus cavernosum would provide a more accurate evaluation of the neurogenic erectile dysfunction patients.