Background: Physical activity promotion within primary health care is in the spotlight. However, few studies have evaluated the long-term effectiveness of possible interventions. This study aimed to compare the effectiveness of 3 primary health care interventions in increasing leisure-time physical activity among older Brazilians. Methods: Experimental study with 142 older residents of an ongoing urban cohort in São Paulo (Brazil). Participants were randomized into 3 groups: minimal intervention group, physician-based counseling group, and individual counseling and referral for physical activity programs group (CRG). We used the long version of the International Physical Activity Questionnaire to assess leisure-time physical activity at baseline, 4 years after baseline without any intervention, 3 months after intervention, and 6 months after intervention. Statistical analysis included repeated analysis of variance. Results: At baseline, 31% of the individuals were active, and this figure remained stable for a period of 4 years. Three months after the interventions, there was a significant increase in leisure-time physical activity for CRG compared with the minimal intervention (P < .001) and physician-based counseling (P < .02) groups, and these differences persisted after 6 months (P < .001 and P < .05, respectively). Conclusion: Results indicate that interventions with CRG are effective in producing sustained changes in physical activity among older Brazilians.