Respiratory infections are the most frequent reason for primary health care consultation. Although generally not severe, they are responsible for a large number of days of laboral and scholar absenteeism and an excessive use of antibiotics.The clinical and epidemiologic data of extrahospitalary infections in primary health care centers throughout Spain were collected according to the one day cut off system repeated trimestrally over one year.Data of 3,732 days of consultation were collected in which a total of 144,608 patients were attended. Of these, 20,614 had respiratory infections and 11,684 extrarespiratory infections. The most frequent processes were pharyngitis (33.7%), common cold (31.7%) followed by bronchitis (18.7%), otitis (11%), influenza (4.6%), laryngitis (4%), sinusitis (3.6%) and pneumonia (1.8%). Antibiotic treatment was prescribed in 13,488 patients (65%). The type of antibiotic was analyzed in the 11,977 patients treated for only one infection. Penicillins were the antibiotics most used followed by cephalosporins. The antibiotic prescribed was considered adequate in 70% of the 8,484 patients treated for potentially bacterial infection. A total of 3,493 patients had infection considered to be of viral etiology.Twenty-two percent of the patients attending a primary health care center presented infection and of these two out of three cases had respiratory infection. Pharyngitis and common cold were the most frequent processes observed. Two thirds of the patients consulting for respiratory infection received antibiotic treatment, with 29.2% being diagnosed with infections considered to be of viral etiology. The empiric treatment chosen for the two thirds of the potentially bacterial infections was considered as adequate.