Background. Figures on GP-diagnosed respiratory tract infections (RTI) are outdated because of demographic changes and increase in co-morbid conditions, respiratory vaccination programmes and change in illness behaviour. Objective. To determine the incidence of RTI in patients presenting to the GP according to age, gender and common high-risk co-morbidity in primary care. Methods. In the Second Dutch National Survey of General Practice 90 computerized general practices with 358 008 patients recorded all consecutive patient contact by use of the ICPC coding system in a year. Incidences were calculated using the mid-year population in the denominator and RTI episodes as the nominator. Results. In all, 4.2% of the patient population were diagnosed with RTI with an incidence rate of 144 per 1000 person-years. Upper RTI were more common in children of 0-4 years than in other year-cohorts [392 versus 80 per 1000; relative risk 4.9, 95% confidence interval (95% CI) 4.8-5.0]. An U-shape association was observed between age and lower RTI (78 and 70 per 1000 in children and persons aged 75 years or over, respectively, versus 23 per 1000 in other age-categories). Females had slightly higher incidence rates of URTI (relative risk 1.4, 95% CI 1.35-1.45) and similar rates for LRTI. Patients with chronic medical conditions as pulmonary and cardiac disease, and diabetes. Discussion. A small proportion of the patient population present themselves to the GP with a RTI. RTI are more common among children, elderly persons and patients with pulmonary and cardiac disease, and diabetes of the ICPC coding system.