Introduction: Acute kidney injury (AKI) is common in hospitalised in intensive care unit (ICU) patients. The reported prevalence of AKI in critically ill patients ranges from 5% to 31% in adult ICU and from 4.5% to 10% in paediatric ICU. The incidents of AKI in ICU depend on several reasons, such as the hospital reference level and structure (surgery clinics and A&E units). Aim of the study: Assess the prevalence of AKI in critically ill children in multidisciplinary hospital with nephrology unit. Methods: We performed a prospective, descriptive epidemiological study assessing incidence of AKI in paediatric ICU patients. The research was conducted over a 1/2-year period. All consecutive admissions to the PICU were included unless they met one of the exclusion criteria, i.e. age <4 weeks of birth, >18 years of age, brain death at entry, expected PICU stay of <24 hours. Patients were classified according to RIFLE score. Results: Acute kidney injury occurred in 13.1% of admissions. The main reason of admission when AKI occurred was congenital heart defect after cardiac surgery (88.5% cases). The mortality rate of patients who met RIFLE criteria for acute kidney injury was 34.6%. Renal replacement therapy was implemented in 30.7% cases of AKI (peritoneal dialysis and continuous venovenous hemodiafiltration) with mortality rate of 88.8%. Conclusions: The study has revealed that the szpitaprevalence of AKI in PICU in multidisciplinary hospital is high with significantly poor outcome. In such a place close interdisciplinary treatment including full availability of renal replacement therapy is a must.