Resumen: Objectives: To measure the diagnostic agreement between Primary Care (PC) and hospital information systems, in order to assess the usefulness of health care records for research purposes. Setting: Cross-sectional retrospective study integrating PC and hospital diagnostic information for the Aragon population admitted to hospital in 2010. Participants: 75.176 patients were analysed. Interventions: Similarities, differences and the kappa index were calculated for each of the diagnoses recorded in both information systems. Main measurements: The studied diseases included COPD, diabetes, hypertension, cerebrovascular disease, ischaemic heart disease, asthma, epilepsy, and heart failure. Results: Diagnostic concordance was higher in men and between 45 and 64 years. Diabetes was the condition showing the highest concordance (kappa index: 0.75), while asthma had the lowest values (kappa index: 0.34). Conclusions: The low concordance between the diagnostic information recorded in PC and in the hospital setting calls for urgent measures to ensure that healthcare professionals have a comprehensive picture of patient''s health problems. Idioma: Español DOI: 10.1016/j.aprim.2015.06.002 Año: 2015 Publicado en: Atencion Primaria (2015), [7 pp] ISSN: 0212-6567 Factor impacto JCR: 1.098 (2015) Categ. JCR: MEDICINE, GENERAL & INTERNAL rank: 83 / 155 = 0.535 (2015) - Q3 - T2 Categ. JCR: PRIMARY HEALTH CARE rank: 15 / 20 = 0.75 (2015) - Q3 - T3 Factor impacto SCIMAGO: 0.262 - Family Practice (Q2) - Medicine (miscellaneous) (Q3)