The most basic treatment for late-onset hypogonadism (LOH) is hormone replacment therapy (HRT). In Japan, intra-muscular injection of testosterone (T) has been used for LOH treatment as HRT. Testosterone ointment (Glowmin) has been available for HRT from 1965 as an over-the-counter drug, and the profile of serum T levels and efficacy of testosterone ointment for LOH patients has been reported. In this study, we analyzed the relationship between the efficacy of testosterone ointment and LOH severity. Fifty LOH patients were treated with 6 mg of testosterone ointment per day. After 12 weeks of treatment, they were divided into 2 groups according to the severity of their LOH, serum total T and free T levels, measured by such means as total aging males' symptoms (AMS) score. The improvements of total AMS score, international index of erectile function 5 score and MOS 36-Item Short-Form Health Survey (SF-36) score were observed and analysis of variation was performed. Results showed that the symptoms in the more severe patients had a total AMS score improvement in 4 domains, AMS (psychological), SF-36 body pain (BP), social function (SF), role-emotion, compared to patients with slight LOH. While patients with normal serum T levels felt BP improvement as opposed to patients with low serum T levels, there was no significant difference in the other domains. In conclusion, testosterone ointment is considered to be effective in improving several elements of AMS and SF-36 in patients with a high AMS score.