The paper describes a radiometric variant of the two-phase titration method for the determination of anionic surfactants of nonsoapy type. The method is based on the titration of an anionic surfactant with Septonex in alkaline medium in the presence of131I-Rose Bengal /abbreviated131I-RB/. The ion associates are extracted into chloroform. The equivalence point is determined graphically from the activity of131I-RB-Septonex associate, which is formed after the consumption of the anionic surfactant and which passes into the organic phase. The influence of131I-RB amount, pH of the titrated medium and of soap presence on the precision of anionic surfactants determination was studied. The detection limit is 2.88 g sodium n-dodecylsulphate in 10 ml of sample.