In healthcare, as in other areas, performance evaluation and outcomes monitoring are an ever increasing priority. This can be accomplished using quality indicators: monitoring and benchmarking tools which allow spatial and temporal comparisons. In the 1990's, following the work of John Billings and colleagues, the Agency for Healthcare Quality and Research (AHRQ), developed a set of area-level Prevention Quality Indicators (PQI), which can be calculated using readily available administrative data. PQIs are based on the concept of avoidable hospitalizations (AH): conditions for which adequate and timely primary care (PC) could have prevented or reduced the need for hospitalization (e.g. heart failure, hypertension, diabetes). We aim to apply these indicators to the Portuguese national health system (NHS), a state-financed universal coverage system, and ascertain time and regional trends and the AH financial and mortality burden.