The current study aimed to investigate the effects of group reminiscence therapy on cognitive function, depression, neuropsychiatric symptoms, and activities of daily living in patients with mild-to-moderate Alzheimer disease (AD). A single-blind randomized parallel-design controlled trial was conducted between May 1, 2017, and April 30, 2018. Ninety patients with mild-to-moderate AD recruited from Beijing Geriatric Hospital were randomly allocated into intervention (n = 45) and control groups (n = 45). In the intervention group, group-based reminiscence therapy was performed in two 30- to 45-minute sessions weekly for 12 weeks. Control participants received only conventional drug treatments and routine daily care. Alzheimer disease–related symptoms were evaluated using the Alzheimer’s Disease Assessment Scale-Cognitive section, the Cornell Scale for Depression in Dementia (CSDD), the Neuropsychiatric Inventory, and the Barthel Index. Four time points were set for data collection: baseline (before treatment), 4 weeks (during treatment), 12 weeks (end of treatment), and 24 weeks (12 weeks posttreatment). χ² Tests, independent t tests, repeated-measures analysis of variance, and Bonferroni tests were used for data analysis. Significant improvements in depressive and neuropsychiatric symptoms were found in the intervention group compared to the control group ( P < .05). Mean CSDD scores in the intervention group were improved at all 3 time points compared to baseline and showed the greatest effect at 12 weeks ( t = 2.076, P = .041) and 24 weeks follow-up ( t = 3.834, P = .000) compared to controls. Group reminiscence therapy was effective for improving depressive symptoms and was beneficial for treating neuropsychiatric symptoms in patients with AD.