Objective@#The rapid identification and treatment of an acute kidney injury (AKI) can help to restore the kidney function. To differentiate between pre-renal AKI and intrinsic AKI, a urinechemistry test was performed to determine the function of the renal tubules. On the other hand, there is no report showing that it is helpful to arrive at the hospital as early as possible and to perform these urinechemistry tests as soon as possible. @*Methods@#This study analyzed the timing of urinary chemistry tests in AKI patientswho were admitted to the author’s hospital through the emergency departments (ED) in the last three years and divided into two groups. The early group was defined as patientswho performed the test within three hours of arrival in the ED. The late group was defined as patientswho were late or not. The prognostic factors were the change in 30-day estimated glomerular filtration rate (eGFR) and duration of hospital stay. @*Results@#The changes of eGFR after 30 days in each group were 41.6±27.57 mL/min/1.73 m2 (early group, n=92) vs. 30.39±26.37 mL/min/1.73 m2 (late group, n=180) (P=0.001). Early group patients were discharged more quickly than patients in the late group (hospital day, 11.49±10.14 vs. 13.84±10.53; P=0.041). @*Conclusion@#A urinechemistry test is a test to help determine the cause of AKI. Based on the results of urinechemistry performed within three hours after arrival at the hospital, patients with AKI who visited the emergency room had betterimproved kidney function and less hospitalizationtime than the patientswho were late or untested at the time of treatment.