BACKGROUND: Health systems have a critical role in a multi-sectoral response to domestic violence against women (DVAW). However, the evidence on interventions is skewed towards high income countries, and evidence based interventions are not easily transferred to low-and middle-income countries (LMIC) where significant social, cultural and economic differences exist. We evaluated feasibility and acceptability of implementation of an intervention (HERA-Healthcare Responding to Violence and Abuse) to improve the response to DVAW in two primary health care clinics (PHC) in Brazil. METHODS: The study design is a mixed method process and outcome evaluation, based on training attendance records, semi-structured interviews (with 13 Primary Health Care (PHC) providers, two clinic directors and two women who disclosed domestic violence), and identification and referral data from the Brazilian Epidemiological Surveillance System (SINAN). RESULTS: HERA was feasible and acceptable to women and PHC providers, increased providers' readiness to identify DVAW and diversified referrals outside the health system. The training enhanced the confidence and skills of PHC providers to ask directly about violence and respond to women's disclosures using a women centred, gender and human rights perspective. PHC providers felt safe and supported when dealing with DVAW because HERA emphasised clear roles and collective action within the clinical team. A number of challenges affected implementation including: differential managerial support for the Núcleo de Prevenção da Violência (Violence Prevention Nucleus-NPV) relating to the allocation of resources, monitoring progress and giving feedback; a lack of higher level institutional endorsement prioritising DVAW work; staff turnover; a lack of feedback from external support services to PHC clinics regarding DVAW cases; and inconsistent practices regarding documentation of DVAW. CONCLUSION: Training should be accompanied by system-wide institutional change including active (as opposed to passive) management support, allocation of resources to support roles within the NPV, locally adapted protocols and guidelines, monitoring progress and feedback. Communication and coordination with external support services and documentation systems are crucial and need improvement. DVAW should be prioritised within leadership and governance structures, for example, by including DVAW work as a specific commissioning goal.