This study aimed to measure the performance of primary health care centres in Eastern province, Saudi Arabia, using the WHO/International Network of Rational Use of Drugs patient care and facility-specific drug use indicators. In a cross-sectional study, 10 health centres were selected using systematic random sampling. A total of 300 patients were interviewed while visiting the centre from January to March 2011 and 10 pharmacists from the same centres were interviewed. Average consultation time was 7.3 min (optimal ≥ 30 min), percentage of drugs adequately labelled was 10% (optimal 100%) and patient’s knowledge of correct dosage was 79.3% (optimal 100%). The percentage of key drugs in stock was only 59.2% (optimal 100%). An overall index of rational facility-specific drug use was calculated and applied to rank the health centres for benchmarking.