Background This study aimed to assess the impact of a group music intervention on anxiety and depression of elderly male veterans with dementia. Material/Methods In total, 50 elderly men with Alzheimer disease were randomly divided into intervention and control groups. Patients in the intervention group attended a 60-minute group music session that used percussion instruments with familiar music in the morning once a week for 12 weeks, whereas those in the control group received a rest and reading session at the same intervals and under the same conditions. The Hamilton Anxiety Rating Scale and Geriatric Depression Scale were used to assess anxiety and depression at baseline, week 6, and week 12. The Primary Measures of Music Audiation (PMMA) was used to assess musical aptitude at the baseline. Results A significant reduction in the anxiety level following the 12-week music sessions was observed in the intervention group ( P <.001), but there was no significant change in the control group. However, the change in depressive symptoms between the 2 groups was nonsignificant. In the intervention group, when stratifying patients based on music aptitude determined through PMMA assessment, patients with high PMMA scores had significantly reduced anxiety symptoms over time compared with those with low scores. Conclusions For elderly male veterans with dementia, participating in a group music intervention reduced anxiety symptoms. In patients with high musical aptitude, the treatment effects on anxiety reduction were satisfactory. Measures of music aptitude may provide valuable information regarding patients’ response to music intervention.