BACKGROUND:Since the 1970s, many countries have employed the use of the General practitioner group practice, but there is contrasting evidence about its effectiveness. A systematic review was performed to assess whether group practice has a more positive impact compared with the single-handed practice on different aspects of health care. METHODS:A systematic review was conducted by querying electronic databases and reviewing articles published between 1990 and 2012. A quality assessment was performed. The effect of group practice was evaluated by collecting all items analysed by the articles into four main categories: (1) studies of quality (measured in terms of clinical processes) and productivity (measured in terms of throughput), named "Clinical process measures and throughput"; (2) studies exploring physician's opinion--"Doctor's perspective"; (3) studies looking into the use of innovation, information and communication technology (ICT) and quality assurance--"Innovation, ICT and quality assurance"; (4) studies focused on patient's opinion--"Patient's perspective". The results were synthesized according to three levels of scientific evidence. RESULTS:A total of 26 studies were selected. The most studied category was Clinical process measures and throughput (58%). A positive impact of group medicine on "Clinical process measures and throughput", "Doctor's perspective", "Innovation, ICT and quality assurance" was found. There was contrasting evidence considering the "Patient's perspective". CONCLUSIONS:Group practice might be a successful organizational requirement to improve the quality of clinical practice in Primary Health Care. Further comparative studies are needed to investigate the impact of organizational and professional determinants such as physician's economic incentives, mode of payment, size of the groups and multispecialty on the effectiveness of medical primary care.