Background:Happiness has a considerable impact on elderly quality of life. Reminiscence therapy can be an effective intervention in increasing the positive emotions among elderly.Objectives:This study was performed to investigate the effect of reminiscence therapy on Iranian elderly women’s happiness.Patients and Methods:This randomized clinical trial conducted on 32 elderly women (census sampling) attending the jahandidegan daycare elderly center IN Gorgan city, Iran, in 2013. Happiness scores of 4 phases were measured: before, the third session, the sixth session and one month after the intervention. Three instruments were used in this study including a demographic questionnaire, the mini mental state examination test, and Oxford happiness questionnaire. The intervention group participated in six sessions of narrative group reminiscence that were held in three consecutive weeks, two sessions per week. The control group was also participated in six sessions of group discussions that were held in three consecutive weeks, two sessions per week. Data analysis was performed the chi-square, independent t-test, Paired t-test.Results:From a total of 32 elderly women, 29 cases completed the study. No significant differences were found between the two groups in terms of demographic characteristics. The mean happiness scores before the intervention between the two groups were not significantly different (P = 0.824). Comparison of the mean happiness scores of the intervention group in the four measurement times revealed a significant difference only after the third and sixth sessions (P = 0.03), and no significant difference was found between the mean happiness scores of the control group in the four measurement times.Conclusions:The elderly participating in the matched group sessions can be effective in increasing positive emotions.