Heart failure (HF) is a serious public health problem worldwide. It has a high prevalence, affects mainly the elderly and causes high mortality or disability with high economic costs. The aim of the present study was to calculate the number of admissions for HF, the total in-hospital stay, the mean length of in-hospital stay and the in-hospital costs due to HF in Belgium. Retrospective analysis of data from the national hospital registration system provided the following results. In 2001, there were 19,398 admissions with HF as a primary diagnosis, with a total in-hospital stay of 286,938 days. The mean in-hospital stay for HF was 14.8 days. The total in-hospital cost of HF as a primary diagnosis was euro 94,113,827, representing 1.8% of the total hospital expenditure. The limitations of this study are its mere focus on admissions and their characteristics in 2001, and the use of a retrospective analysis. Nevertheless, it led to the conclusion that HF was responsible for a significant number of in-hospital days, with a significant impact on healthcare costs in Belgium.