What factors are associated with adherence of older adults to group exercise interventions for the prevention of falls? What is the relationship between adherence and the falls prevention efficacy of the intervention? Design: Systematic review with meta-analysis of randomised trials. Participants: Older adults (60 years and older) undertaking a group exercise intervention for falls prevention. Intervention: Group exercise not in combination with a home program and intended at least in part for falls prevention. Outcome measures: Adherence was measured as the mean proportion of sessions attended, including participants who discontinued the intervention. Falls prevention efficacy was measured as the proportion of fallers in the intervention versus the control group at follow-up. Various program-related factors, including intervention duration, session frequency, and components of the exercise regimen were examined for each of the studies. Results: Of the 210 articles identified, 18 studies met the inclusion criteria and were analysed. The pooled estimate of adherence across the studies was 0.74 (95 CI 0.67 to 0.80). Lower levels of adherence were associated with group exercise interventions that had a duration of 20 weeks or more, two or fewer sessions per week, or a flexibility component. No significant relationship was found between adherence and falls prevention efficacy. Conclusion: Program-related factors may influence adherence to group exercise interventions for the prevention of falls. Further research is encouraged to more precisely determine the effect of intervention level factors on adherence, and the effect of adherence on intervention efficacy.