Abstract: Acetylsalicylic acid is unique among the Non-steriodal Anti-Inflammatory Drugs (NSAIDs) in irreversibly acetylated cyclooxygenase. Renal clearance of endogenous creatinine and salicylate (as free salicylic acid) was investigated in twelve healthy female volunteers after oral dose of 600 mg soluble aspirin. Blood and urine samples were collected at predetermined time intervals. The concentration of free salicylic acid and creatinine in plasma and urine was determined colorimetrically. The average ±SE values, for free salicylic acid in plasma was 25.569±0.60 and in urine was 37.892±4.537 μgmL–1, for diuresis 0.034±0.005 mlmin–1kg–1, concentration of creatinine in plasma was 14.16±0.55 and in urine was 493.22±62.5 μgmL–1, renal clearance of creatinine was 1.438±0.30 and free salicylic acid was 0.082±0.016 mlmin–1kg–1 and clearance ratio was 0.092±0.023. It was found that renal clearance of aspirin was low under indigenous conditions.