Primary care is currently at the heart of health service policy, both in Portugal and internationally. At the same time, interest in the measurement of efficiency of health care delivery has increased considerably. However, very few studies have focused specifically on performance assessment in primary health care provision. In this paper we aim to contribute to a discussion regarding appropriate ways to compare the performance of primary health care providers. Following a review of the literature, a conceptual framework for performance assessment of health centres is developed and tested using the Portuguese case. Our empirical analysis uses data from 2004 and 2005 for all the Portuguese health centres and compares the geographical equity of access to services, technical efficiency and quality of services across District Health Authorities. Data Envelopment Analysis is the technique used to measure technical efficiency. From our empirical analysis, we conclude that there is evidence of large variation in equity of access to services, in technical efficiency and quality of services across District Health Authorities. Our findings suggest that a better use of resources could lead to more and improved services. Whilst formative evaluation could contribute to this, the challenge is to engage health care professionals in the evaluation exercise.