Abstract: This paper deals with controlled release of drug based on the principle of chemical engineering. The comprehensive kinetic models for monolithic matrix are derived and the internal diffusional process is discussed. The models are tested by the polyCethylene -vinyl al-cohol)/5 - Fluorouracilum(EVAL/5 -FU)matrix system. The results show that the models, which can theoretically support the hypotheses of Higuchis model, agree well with experimental data.