Objective To study the relationship between acute renal failure(ARF) and hyperosmolaremia in stroke patients and the related factors.Methods The clinical data of 59 stroke patients with ARF(ARF group) and 76 stroke patients without ARF(control group) were studied.The correlation analysis was used to compare the serum osmolality levels and serum creatinine values between the two groups.The factors that caused ARF in stroke patients were estimated using a logistic regression model.Results The mean serum osmolality in ARF group[((320.98?)30.63)mOsm/L] was significantly higher than that in control group [((295.49?)17.7)mOsm/L]((P