Objectives: With regard to increasing aging population in Iran, depression severely decreases the “quality of life” in this age group and successively seclusion and getting away from society and social activities will ensue. Therefore, this study aimed to determine the relationship between “quality of life” and depression among the retired older people. 
Methods & Materials:  This cross-sectional and correlational study included 200 retired elderly people who worked in Ahvaz Oil Industry, Iran using convenience sampling method. The data were collected by the quality of life questionnaire (SF-12) and depression questionnaire (GDS) and then analyzed by the Pearson correlation coefficient, ANOVA, and regression analysis using SPSS version 16. 
Results: It was found that the older people in the age range of 61–65 years had the highest frequency (46.5%) and the older people in the age ranges of 71–75 and 76–80 years had the lowest frequencies (0% and 5%, respectively). In this study, the mean (SD) age of the participants was 65 (4) years. The older people in different age groups expressed pretty similar “quality of life” and depression signs and symptoms, and there were no significant differences among them with respect to dependent variables (“quality of life” and depression) (P>0.05, F=1.57). In terms of education, the highest frequency was seen in the under diploma group (44%), and the lowest frequency was seen in the postgraduate group (1.5%). With regard to the history of internal diseases, the elderly with hypertension had the highest frequency (37%). The mean (SD) score of “quality of life” among the old subjects was 27.9 (6.4) and depression signs and symptoms was 4.35(4.2). There is a significant and negative relationship between depression and “quality of life” among the elderly (P<0.001). Moreover, the prediction of depression signs and symptoms is significant based on the dimensions of “quality of life” (physical and mental dimensions) (P<0.05, F=1.57). There were significant differences between normal elderly people and sick elderly people who suffered from diabetes, hypertension, or cancer with respect to “quality of life.” 
Conclusion: Our study results showed a significant relationship between depression and “quality of life” in the old age. Therefore, the relevant factors to the “quality of life” among the older people must be considered. The self-confidence in the elderly people can be increased by establishing peaceful relations, involving them in constructive activities, and by promoting hope for their future. Prevention and reducing the causes of depression a well as its treatment can improve the quality of life for the older people.