Wearable technology is progressively applied in health care and rehabilitation to provide objective insight into physical activity levels. In addition, feedback on physical activity levels delivered by wearable monitors might be beneficial for optimizing their physical activity. A systematic review and meta-analysis was conducted to evaluate the effectiveness of interventions using feedback on objectively measured physical activity in patient populations. Fourteen studies including 1902 patients were analyzed. Overall, the physical activity levels of the intervention groups receiving objective feedback on physical activity improved, compared to the control groups receiving no objective feedback. Mostly, a variety of other strategies were applied in the interventions next to wearable technology. Together with wearable technology, behavioral change strategies, such as goalsetting and action planning seem to be an important ingredient to promote physical activity in health care and rehabilitation. Objective: To determine the effectiveness of health care interventions promoting physical activity, which use objective feedback on physical activity delivered using wearable activity monitors as part of the in tervention. Intervention groups are compared with control groups receiving usual care or interventions without objective feedback. Data sources: PubMed, EMBASE, MEDLINE and Co chrane Library were searched to identify randomized controlled trials. Study selection: Randomized controlled trials pu blished after 2007 with (former) healthcare patients ≥ 21 years of age were included if physical activity was measured objectively using a wearable moni tor for both feedback and outcome assessment. The main goal of included studies was promoting phy sical activity. Any concurrent strategies were related only to promoting physical activity. Data extraction: Effect sizes were calculated using a fixed-effects model with standardized mean dif ference. Information on study characteristics and interventions strategies were extracted from study descriptions. Data synthesis: Fourteen studies met the inclusion criteria (total n = 1,902), and 2 studies were exclu ded from metaanalysis. The overall effect size was in favour of the intervention groups (0.34, 95% CI 0.23-0.44, p < 0.01). Study characteristics and inter vention strategies varied widely. Conclusion: Healthcare interventions using feedback on objectively monitored physical activity have a moderately positive effect on levels of physical acti vity. Further research is needed to determine which strategies are most effective to promote physical ac tivity in healthcare programmes.