In a prevalence study of septicaemia at a surgical clinic 645 patients were followed up. The assembled data were compared with data from a similar study made in 862 patients which was implemented in different departments of Ostrava hospitals. In the two studies different criteria of sepsis were used. In the study conducted at the surgical clinic these criteria were more precisely specified and extended. This trebled the assessed number of sepses. From comparison of results of these studies ensues that more frequent bacteriological monitoring of patients in necessary.