Background: Alzheimer is a disease leading to various neuropsychiatric behavioral disorders, and the most common symptom observed during the prognosis of Alzheimer's disease is dysmnesia. The aim of the present study is to investigate the effect of reminiscence therapy on cognitive functions, depression, and quality of life in Alzheimer's patients. Methods: The present study was a randomized controlled single blind study with two groups, which was designed in the experimental pretest-posttest pattern in the city of Konya, Turkey. It was decided to include a total of 60 elderly individuals. Information form that evaluated socio-demographic characteristics and disease history of individuals in intervention and control groups and was developed by the researcher. Standardized Mini-Mental State Examination (SMMSE), Cornell Scale for Depression in Dementia, and the Quality of Life in Alzheimer's Disease (QOL-AD) Scale were used to collect the data. Reminiscence therapy was applied once a week and lasted for 8 weeks. Every session took 60 minutes. Groups consisted of six people. Results: Mini-Mental Test, depression, and quality of life mean scores of the elderly in intervention group before reminiscence therapy program increased after the administration, and the difference was statistically significant (P < 0.05). In the intergroup comparison, a significant difference was found between elderly individuals' posttest Mini-Mental Test, depression, and quality of life mean scores (P < 0.05). Conclusions: Our results suggest that regular reminiscence therapy should be considered for inclusion as routine care for the improvement of cognitive functions, depressive symptoms, and quality of life in elderly people with Alzheimer.