Background: Hospital costs are a concern to health care managers and health politicians, not least because of the demographic changes we can expect over the next 25 years. To plan for the future, it is important to understand the current cost structure of hospitals. Previous research has shown that relatively small proportions of the population account for large proportions of the costs. Objective: To identify demographic and clinical characteristics of patients with high resource consumption who were treated at somatic hospitals. Method: Data on use of hospital care and of costs for 2008 was obtained from the Norwegian patient registry. The data was aggregated from the episode-of-care to the patient-level and subsequently analysed descriptive according to age, gender, type of treatment (major diagnostic categories and principle diagnoses). Costs were obtained using DRG-weights. Cost deciles were created based on each patient s aggregate cost during 2008. The top decile and subgroup of the top 5% and 1% were further examined for principle diagnose. Results: The highest cost consuming patients accounted for over of 50% of the costs, whereas the top 5% and 1% consumed 30% and 13%, respectively. High cost patients (top 10%) accounted for 32% of care episodes and 38% of total days spent at hospital. Age groups 60-69 and 70-79 had the highest proportions of total costs and number of total care episodes. Overall, more women were treated at hospital, but men cost on average more to treat. The two principle diagnoses that accounted for the majority of total aggregate costs were associated with musculoskeletal system and connective tissue (18%), and the circulatory system (12%). The most resource consuming treatments were for DRG 209A (primary prosthesis operation hip/knee/ankle) and DRG 383 (tracheostomy), one with a fairly large number of care episodes and one with relatively low number of care episodes. Treatment episodes for conditions such chronic lower respiratory diseases (especially, ICD-10 J15 and J44) were also frequent. Conclusions: High cost patients are not necessarily resource demanding because of a few high cost treatments but rather the sum of many care episodes makes them more resource demanding. However, individual health costs have a large random component. This means that being a high cost patient one year does not necessarily mean that he or she is a high cost patient later.