Acute kidney injury (AKI) is associated with poor prognosis among patients with acute heart failure (AHF). Early documentation of impaired kidney function through simple examination may provide risk reduction in such patients. The present study aims to reveal an association between cellular casts and hospital-acquired AKI in AHF. This study included patients with AHF who underwent urinalysis, including urinary sediment analysis within 24 hours post admission. AKI was defined as an increase of ≥0.3 mg/dL within 48 hours or ≥1.5 times in serum creatinine level in contrast to baseline creatinine level. In this study, 114 patients with AHF (age, 75 ± 14 years; male, 59.7%) were included. Of them, 40 (35%) developed hospital-acquired AKI. Cellular casts were detected in 30 patients (26%) prior to AKI development and related to hospital-acquired AKI in the multivariate logistic regression analysis (odds ratio, 2.80; 95% confidence interval, 1.04-7.49; P = 0.041). In conclusion, cellular casts are observed occasionally in patients with AHF and potentially useful markers for development of AKI during hospitalization.