BACKGROUND Acute kidney injury (AKI) is associated with a high mortality. This study was undertaken to detect the factors associated with the prognosis of AKI. METHODS We retrospectively reviewed 98 patients with AKI treated from March 2008 to August 2009 at this hospital. In these patients, 60 were male and 38 female. Their age ranged from 19 to 89 years (mean 52.4±16.1 years). The excluded patients were those who died within 24 hours after admission to ICU or those who had a history of chronic kidney disease or incomplete data. After 60 days of treatment, the patients were divided into a survival group and a death group. Clinical data including gender, age, history of chronic diseases, the worst laboratory values within 24 hours after diagnosis (values of routine blood tests, blood gas analysis, liver and renal function, levels of serum cystatin C, and blood electrolytes) were analyzed. Acute physiology, chronic health evaluation (APACHE) II scores and 60-day mortality were calculated. Univariate analysis was performed to find variables relevant to prognosis, odds ratio (OR) and 95% confidence interval (CI). Multiple-factor analysis with logistic regression analysis was made to analyze the correlation between risk factors and mortality. RESULTS The 60-day mortality was 34.7% (34/98). The APACHE II score of the death group was higher than that of the survival group (17.4±4.3 vs. 14.2±4.8, P<0.05). The mortality of the patients with a high level of cystatin C>1.3 mg/L was higher than that of the patients with a low level of cystatin C (<1.3 mg/L) (50% vs. 20%, P<0.05). The univariate analysis indicated that organ failures≥2, oliguria, APACHE II>15 scores, cystatin C>1.3 mg/L, cystatin C>1.3 mg/L+APACHE II>15 scores were the risk factors of AKI. Logistic regression analysis, however, showed that organ failures≥2, oliguria, cystatin C>1.3 mg/L +APACHE II>15 scores were the independent risk factors of AKI. CONCLUSIONS Cystatin C>1.3 mg/L+APACHE II>15 scores is useful in predicting adverse clinical outcomes in patients with AKI.