Background Performance-based financing (PBF) is an increasingly adopted strategy in low-and middle-income countries. PBF pilot projects started in Burundi in 2006, at the same time when a national policy removed user fees for pregnant women and children below 5 years old. Methods PBF was gradually extended to the 17 provinces of the country. This roll-out and data from the national health information system are exploited to assess the impact of PBF on the use of health-care services. Results PBF is associated with an increase in the number of anti-tetanus vaccination of pregnant women (around รพ20 percentage points in target population, P < 0.10). Non-robust positive effects are also found on institutional deliveries and prenatal consultations. Changes in outpatient visits, postnatal visits and children vaccinations are not significantly correlated with PBF. It is also found that more qualified nurses headed to PBF-supported provinces. The limited quality of the data and the restricted size of the sample have to be taken into account when interpreting these results. Health facility-level figures from PBF-supported provinces show that most indicators but those relative to preventive care are growing through time. Discussion The dataset does not include indicators of the quality of care and does not allow to assess whether changes associated with PBF are resource-driven or due to the incentive mechanism itself. The results are largely consistent with other impact evaluations conducted in Burundi and Rwanda. The fact that PBF is mostly associated with positive changes in the use of services that became free suggests an important interaction effect between the two strategies. A possible explanation is that the removal of user fees increases accessibility to health care and acts on the demand side while PBF gives medical staff incentives for improving the provision of services. More empirical research is needed to understand the sustainability of (the incentive mechanism of) PBF and the interaction between PBF and other health policies. In Burundi, the implementation of performance-based financing (PBF) schemes is associated with an increase in the use of some maternal and child health-care services. PBF has no visible impact on the use of other services. It is suspected that a substantial part of the apparently positive correlation between PBF and the use of maternal and child health-care services is due to the interaction between PBF and the removal of user fees for pregnant women and children below 5 years old. PBF supposedly acted on improving the supply of services while free health-care services led to an increase in demand. It remains complicated to assess what exactly led to a positive impact on the use of maternal and child health-care service; in particular, the exact role of the PBF incentive mechanisms could not be pinpointed. More research is needed, and should be designed before PBF projects are implemented……more