Abstract: A simple and accurate method for colorimetric micredetermination of antimony in biological materials has been investigated. Procedure: Weigh out liver tissue (up to 1.5 g),or whole blood (up to 4g),and into a conical flask. Add 1 ml of perchloric acid, 3—3.5 ml of concentrated nitric acid, 3.5 ml of concentrated sulphuric acid. Digestion commences spontaneously. Add a few glass beads and one drop of capryl alcohol.Place the flask on a sand bath, keep the temperature at 50—150℃ for 15 minutes.then raise the temperature to 150—250℃ for 15 minutes, thereafter maintain the temperature between 250—300℃ for half an hour, and finally 320±20℃ for 15—30 minutes. The digestion is finished. The digestive solution may be charring but this does not affect the determination. When the solution is cooled, add 3ml of water,6 ml of 6 N HCl and 0.2 ml of 2% ceric sulphate. Pour the solution into a test tube equipped with a stopper or a separatory funnel, add 6.0 ml of amyl acetate or toluene-ethyl acetate(1:1 v/v)mixture. Shake 200 times, and separate,then transfer the superficial solvent into another test tube. Add 1 ml of 0.4% brilliant green and 9 ml of 0.2N HCl,shake 200 times,and centrifuge.Pour off 3 to 5 ml into cuvette for estimation of colour. The blank and antimony of standard are used with corresponding solvent treated with the same procedure but without digestion. Iron could be present without interfering with the determination in this experimental condition. This method has been proved satisfactory in the determination of antimony in both blood and liver tissue.