Hormone replacement therapy (HRT) is performed for the treatment for patients with late onset hypogonadism (LOH). One of the main concerns about HRT is the influence of lower urinary tract including prostate. This study examined whether HRT for Japanese patients of LOH affected lower urinary tract symptoms. A total of 21 patients with LOH were included in this study. Changes of International prostate symptom score (IPSS), IPSS quality of life (QOL) index and King's health questionnaire (KHQ), before HRT and 3 months after HRT, were evaluated. Statistical comparisons were made using the Wilcoxon signed rank test, P < 0.05 was considered statistically significant. Total IPSS and QOL index were not significantly different from 7.43 +/- 6.56, 2.71 +/- 1.74 at baseline to 8.29 +/- 6.24, 2.91 +/- 1.13 after 3 months. There were no significant differences in any of the nine categories of KHQ. In this preliminary study, the results suggested that HRT for LOH had no short-term effects on patients with lower urinary symptoms.