It is often difficult to differentiate acute renal failure (ARF) from chronic renal failure (CRF) when the patient presents with advanced uremia for the first time. Assessments of kidney size, history of nocturia, and pallor are used as indirect indicators of CRF. Some investigators have proposed an estimation of finger nail creatinine concentrations to differentiate between ARF and CRF, as patients with CRF have higher nail creatinine concentrations. Measurement of creatinine in the nail can be performed easily in a biochemistry laboratory. The nail clippings are cleaned, dried, pulverized and creatinine extracted from the powdered nail to be assessed biochemically. By standardizing the methods, the biochemistry laboratory can provide the results within 48 hours. In this study, we analyzed the nail clippings of 49 normal subjects, 50 cases of known acute kidney injury (AKI), and 50 cases of known CRF on follow-up at the Nephrology Clinic, Medical College, Trivandrum between December 1999 to November 2000. Forty-nine normal individuals were selected from healthy bystanders of respective patients. On study, it was revealed that patients with ARF had a mean fingernail creatinine level of 30.9 mg/100 g of nail as against 30.1 mg/100 g of nail in normal controls. There was no difference between the controls and ARF patients.Patients with known CRF had a mean fingernail creatinine level of 69.2 mg/100 g. There was a significant increase in the level of nail creatinine in patients with known CRF versus ARF patients and normal controls. The measurement of nail creatinine is useful, easy and can be standardized and performed in a biochemistry laboratory. This simple investigation can help in solving the question of ARF versus CRF in a given case. From this study, it is concluded that the result of creatinine concentrations of nail clippings can indicate chronicity of renal failure.