['The electronic health record (EHR) allows a detailed study of the primary care consultations and assessment of variability among physicians regarding the implementation of practices for prevention, detection and monitoring of chronic diseases.', 'To describe the variability in the detection and surveillance of chronic conditions in primary care.', 'Review of the medical records maintained by 1685 primary care physicians in the Basque Health Service. Estimation of age and sex standardized rates of compliance with evidence-based recommendations and the systematic component of variation (SCV).', 'Compliance with screening recommendations varied from 14.2% for chronic obstructive pulmonary disease (COPD) to 37.2% for hypercholesterolaemia of the at-risk populations. Variability between Primary Care Units (PCUs) was low (SCV(5) (-95) < 0.10) for high blood pressure, hypercholesterolaemia and diabetes and high (SCV(5) (-95) ≥ 0.20) for COPD. Based on the EHR registries, recommendations were followed to in at least 50% of relevant patients according to only 10 of the 44 good care practice (GCP) criteria. For 16 of the GCP criteria, the EHR data indicated compliance to the recommendations in <25% of patients diagnosed.'] Is variability in the detection and monitoring of chronic patients in primary care according to what registered in the electronic health record?