OBJECTIVES: to estimate the natural history of influenza and the associated resource utilization and General Practitiones (GPs) workload in the Italian general population. METHODS: during a three-month winter epidemic period, 199 GPs from one Northern and one Southern Italian region reported daily the number of visits because of Influenza-like-illness (ILI), Clinical influenza (CI) and any other cause. Furthermore, the first 10 cases of CI in each month of the three-month period (a total of 30 cases per GP), were carefully recorded and followed up. RESULTS: about 200,000 visits were performed by 199 GPs. ILI and CI accounted for 13.8% and 8.3% of all visits respectively. Six thousand and fifty seven cases of CI were collected and evaluated for outcomes. In our sample, 20% of patients (pts) were at risk because of age (?65 years) or concurrent conditions. Almost all pts received at least one prescription for symptomatic drugs, and 36% received antibiotics. Complications (primarily upper and lower respiratory tract bacterial infections) affected 35% of pts. At risk pts had significantly higher complication rate (OR=2.89; 95%C.I. 2.44-3.41), and required more exams and hospitalizations than other pts, accounting for most of direct costs associated with CI. Pts with CI had an average of 5 days of absence from work or school. CONCLUSIONS: influenza is associated with significant morbidity in general and at risk population, considerable working days lost and sizeable excess workload for GPs.