Abstract: The changes of biological properties of cultured color ectal carcinoma(CCL-187)were studied during induced by all-trans retinoic acid(RA),such as cell growth、cell surface morphology、 ultramicroscopic structure、activity of alkaline phosphatase and activity of endoplasmic marker glucose-6-phosphatase.The results showed that the growth of CCL-187 cells could be inhibited under 5Lm RA significantly surface features of cells became regular. filopodia and surface blebs disappeared but blunt extensions appeared;the ultrathin sectioning displayed organelles such as mitochondr ia and endoplasmic reticulum were increased;activity of al-kaline phosphatase was 23.4% higher than control cells after treated with 5LM retinoic acid,and activity of glucose-6-phosphatase was higher than untreated cells,too.The results indicated that RA could induced colorectal carcinoma differentiation.