The purpose of this study was to investigate and compare the participation motives of male and female older adults for sport activities. The subjects were 241 persons (121 men and 120 women ranged from 60 to 89 years old, M = 66.16, SD = 6.66) who were selected from 5 districts of Tehran by relative portion method. Data were collected using demographic questionnaire and participation motivation questionnaire for older adults (PMQOA). The descriptive statistics, Friedman test and one-way analysis of variance (ANOVA) were used to describe variables and to test the research hypotheses. Results indicated significant differences in the priority of different factors of participation motives (X2 = 556.4, P=0.00); and fitness motive was the most important reason for sport participation in older adults. There were significant differences between men and women in “medical” and “reputation” factors (P<0.05) and women reported these factors as more important for their participation in sport activities when compared with men. In addition, the results indicated significant differences among age groups in “social”, “challenge – benefit” and “involvement” factors (P<0.05), and 60-69-year-old group rated these motivation factors higher than 70-year-old and older group. There were significant differences among different educational levels in “reputation”, “medical” and “involvement” factors (P<0.05). The homemakers also placed greater emphasis on “medical” factor when compared with military subjects. The findings of this study can be useful to develop exercise interventions for older adults which could increase exercise participation.