OBJECTIVES: Estimates of fixed funding budgets can only be accurate if all pathology related insurance costs are considered.In this work we analysed the predictive value of LOS and PT cost on TH insurance cost as surrogates for total budget estimation.These predictors may already be available prior to the various other cost elements and act as management indicators. METHODS: Belgian hospitals register admission data in MBDS; the Health Authorities make annual data freely available via the web (https://tct.fgov.be/etct/) on insurance costs (medicines, medical or surgical procedures, laboratory requests, others) relating to hospital stays per All Patients Refined Diagnosis Related Groups (APRDRG) and per stay severity. Data from the year 2000 were analyzed in SPSSWIN12.0 using multiple forward stepwise linear regression. For each variable the median value was used.Data transformations were used if appropriate. RESULTS: On APRDRG-level median TH-cost was significantly correlated to HS-cost (r=0.858, p<0.0001) and PT-cost (r=0.708, p<0.0001). Median TH-cost increased with stay severity (minor 1728 Euro, extreme 8984 Euro).The linear regression model considered the inclusion of the factors LOS, PT-cost, mean patient age and stay severity on TH-cost ; the selected model had an adjusted R² = 0.767 and included LOS (change in R² = 0.691), PT-cost (change in R² = 0.038) and minor to moderate severity (all factors with p<0.001).The model fitted the data of > 340 APRDRGs; liver transplantation, major cardio-vascular surgery, threatened abortion and alcohol abuse may benefit from specific modeling. CONCLUSIONS: LOS and pharmaceutical treatment cost allow to explain > 70% of the variance of the total hospital-cost as measured in real life MBDS-data; these predictors may be useful as budget management indicators for a majority of APRDRGs before detailed financial data become available.