Objectives: The objective of the study was to identify the incidence of acute kidney injury (AKI) in patients in the intensive care unit (ICU), to confirm the risk factors responsible for insufficient kidney function, to evaluate a level of AKI and to which extent it affects the hospital outcome. Study design: A retrospective study. Participants and methods: The participants included in the study were patients (admitted to the ICU for the observed period from January 1. 2015. to December 31. 2016.), whose state deteriorated with AKI. Left out from the study were cardiosurgical patients, those on hemodialysis and also those who spent more than 3 days in the ICU. Data relevant to the study were collected from medical histories and calculations were done using the statistical package R (version 3.2.0). Results: AKI was diagnosed in 131 patients within 48 hours upon their admission to the ICU. According to KDIGO classification, in 51.2 % of the patients the disease developed to level 2, in 42.2 % to level 3. Two thirds of the participants were surgical patients admitted to the ICU after a planned or an emergency operation. Associated diseases included high blood pressure, congestive heart failure and diabetes. Conservative treatment was used in 80.9 % cases, hemodialysis in 19.1 %. 73.3 % of the patients died, mainly those with 2 and 3 KDIGO disease level. Conclusion: AKI early incidence may suggest that AKI developed prior to the admittance to the ICU, and was most probably correlated with the basic disease. High SAPS and SOFA scores indicate severely damaged health and an occurence of AKI within MODS. Besides surgical disease as the most plausible risk factor, other potentially contributing risks are hipertension, congestive heart failure and diabetes. Severe cases of AKI may lead to death in high risk patients.