Information on the prevalence of bacterial cellulitis (BC) and erysipelas (ER) of the leg (BCERL) is sparse and dependent on the definitions used. There is no information available on the number of hospitalized and non-hospitalized patients with BCRL, and related treatment costs. The purpose of this study was to assess the burden of illness for BCERL in the Netherlands in 2001. Data were obtained from different linked databases. Hospital information was obtained from the National Morbidity Registration (known in the Netherlands as the LMR), which includes all Dutch citizens, using ICD-9-CM codes. The number of patients not admitted to hospital was estimated using a subsample with data from general practitioners (GPs) (N = 50 000). These data wereextrapolated using age/gender and disease-specific standardization. The subsample was used to assess the location of the infection. Reimbursement costs were available for all resources. In 2001, approximately 28 000 patients presented with either BC orER of the leg. Of these patients, 2200 were admitted to the hospital and 4-6% had two or more episodes of ER/BC in 2001. The average costs per hospitalization for BCERL were 5346 euros, accumulating to more than 14 million euros in 2001. Although only 7%of all patients were hospitalized, 83% of the total treatment costs could be attributed to hospitalization. BCERL are common and serious infections in the Netherlands. Hospitalization occurs in only one in 14 patients but contributes more than 80% of the total costs, which accumulate to 17 million euros a year.