Abstract: The objective of the study was to evaluate the renal clearance of levofloxacin and that of the endogenous creatinine, following a single oral dose of 500 mg of levofloxacin to eight healthy male volunteers. After an over night fasting control and after drug administration blood and urine samples were collected at 0,30, 60, 90, 120, 150 and 0, 45 ,75, 105, 135 ,160 minutes time intervals, respectively. The samples were assayed for endogenous creatinine spectrophotometrically and levofloxacin by microbiological assay. Mean± SE values for the blood and urine pH were 7.548 ± 0.013 and 5.85 ± 0.0039, respectively. The average±SE value for diuresis was 0.018± 0.0056ml min-1 kg-1. The average± SE values for renal clearance of endogenous creatinine and levofloxacin were 0.519±0.068 and 0.778±0.110ml min-1 kg-1. The study performed in summer showed that with an increase in urine flow the renal clearance of levofloxacin also increase, and statistically there is non-significant positive correlation (R2=0.647) between these two parameters. These variations in results supporting the findings that there is a need to evaluate the imported drugs under indigenous conditions due to environmental difference, for getting optimal therapeutic results.