The kinetics of tetracycline sorption on the anion exchanger AB-17-2 were found to show a significant dependence on exchanger particle size. Experimental studies demonstrated the transition from gel to mixed and film diffusion during tetracycline sorption when anion exchanger particle size decreased from 800 -1200 mm to 0.1 -1.0 mm, while the coefficients of diffusion were comparable for model and real solutions, varying from 10 10 to 10 7 cm 2 /sec. These data demonstrate potential for the use of anion exchanger AB-17-2 in the extraction and purification of tetracycline.