OBJECTIVES: The IPSS evaluates the frequency of lower urinary tract symptoms (LUTS). The SPI score (Symptom Problem Index) evaluates the degree of discomfort associated with each question on the IPSS. Our objective was to clarify the possibility of a substitution of the IPSS and SPI rating scales. METHODS:The IPSS and SPI questionnaires were self-administered to a cohort of 907 male patients presenting a BPH recently diagnosed. The relationship between SPI and IPSS was investigated through the correlation between the 2 scores and by the classification of each symptom according to its frequency on the one hand, and the bothersomeness that it induces on the other. RESULTS: The mean IPSS score was 12.6 +/- 6.4, the mean SPI score was 12.2 +/- 6.5.The correlation coefficient between the IPSS and SPI scores was 0.70; the scores from the 2 rating scales showed a very high variability. On a 0-100% scale, where 100% represents the maximal possibility, the degree of bothersomeness observed in the cohort ranged from 35 to 55%, the induced bothersomeness ranged from 0 to 22.6% and the frequency of the symptoms observed ranged from 26 to 44% depending on the 7 symptoms. CONCLUSIONS: The two questionnaires do not collect the same information. Considering the importance of bothersomeness associated with lower urinary tract symptoms for making the decision about therapy, the joint use of the IPSS and SPI seems appropriate.