In a retrospective study 192 serum prealbumin (PA) concentrations, routine laboratory parameters, the lenght of stay (LOS) and the Pediatric Risk of Mortality (PRISM) score were evaluated in 80 children. The mean PA level on admission was 113 mg/l (SD = 79), albumin 38 g/l (SD = 7), C-reactive protein (CRP) 96 mg/l (SD = 118). The mortality was much higher in those patients whose PA concentration did not change or finally decreased (12 patients, 50% mortality) compared with those with immediately or finally increased PA values (41 patients, mortality 2%). The protein caloric malnutrition (PCM) risk was assessed by the PA concentrations. In the high risk group the LOS, PRISM score, CRP, CRP/PA ratio were higher, than in the moderate and low risk groups. PA is an indicator of the severity of the disease and nutritional status.