Abstract: A colorimetric method for the determination of chloramphenicol is described. A sample containing 10 mg of chloramphenicol was reduced with 10 ml of 10% hydrochloric acid arid 50 to 100 mg of zinc dust,diluted with water to 500 ml, of which 10 ml was diazotized with 0.5 ml of 10% solution of sodium nitrite, then coupled with a mixture of 10 ml of 5% sodium hydroxide solution and 0.1 ml of a solution of 1% α-naphthol in alcohol for 30 minutes.It was then diluted to 100 ml.The color developed was found to be stable.The optical density was then taken from a B.Lunge's Model Ⅳ Universal Colorimeter using a BG-7 filter (480 mμ),and the result read off from a standard curve previously prepared from a purified sample of racemic chloramphenicol manufactured in our own works. Suitable concentration of chloramphenicol for comparison was found to be between 0.13 and 0.3 mg/10ml.The amount of α-naphthol used was found to influence the result.