The erythropoietin was expressed in Chinese Hamster Ovary (CHO) cells and culture techniques were developed, purification process was developed.Different culture conditions were tried to evaluate the influence of various factors on erythropoietin production expressed in Chinese Hamster Ovary Cells.The productivity was checked at different harvests and found that the EPO expression was stable upto 10 harvest, sialidase activity was checked, effect of addition of sodium butyrate was studied on the productivity of erythropoietin (EPO).