A new specrophotometric method is described for the trace determination of acrylonitrile in wastewater and biological sample. First the traces of acrylonitrile, is oxidized by dilute potassium permanganate into cyanide. The cyanide further reacts with bromine to form cyanogen bromide. The cyanogen bromide reacted with pyridine gives glutaconic aldehyde through the breakage of heterocyclic linkage, which then coupled with 4-amino salicylic acid. In alkaline medium a yellow orange dye formed which is extractable in n- butanol in acid medium. The system obeys Beer’s law from 0.015-0.15 ppm .The extract shows maximum absorbance at 520 nm. Molar Absorpitivity and Sandell’s Sensitivity were found to be 7.4 x 104 l/mol/cm and 0.0007 mg/ cm respectively for extractive system. The Standard Deviation and Relative Standard Deviation were found to be ±0.0073 and + 1.47 % respectively for 10 mg of acrylonitrile in 100 ml. The method has been successfully applied for the determination of acrylonitrile in wastewater, urine, blood, cystein, saliva etc. and compared with other methods.