Migrations of chemicals in rubber blends during processing time have an important effect on vulcanization of rubber phases and finally on the blend properties. However the studies on this problem are mostly concerned the migrations of solid particles such as fillers, that assumed no soluble in rubber phase. Almost no publication on migrations of organic curatives that are soluble in and have chemical reactions with rubbers. In this work, we have studied the migrations of accelerators in blends of natural rubber (NR) and EPDM rubber (NR/EPDM blends) through their vulcanization curves, where NR is considered as fast vulcanized component, and EPDM – very slow one. Firstly, the effect of accelerators on vulcanization rate of each rubber phase were evaluated separately. Then, after blending, the vulcanization curves of NR/EPDM blends were compared with ones of each rubber. Based on their comparison we can evaluate the trends of migrations of accelerators. Two mixing procedures were studied. In first one – cross mixing – the curatives were brought into NR and EPDM separately in various contents provided their total amount in all blends stay equal, and blending was carried out only after that. In second procedure – simple mixing – NR and EPDM were blended first, and then total amount of curatives was mixed in. Results showed the migration of accelerators was reflected clearly on behaviors of vulcanization curves of NR/EPDM blends. For cross mixing procedure the vulcanization rates of blends vary between 0,12 – 0,17 lbf/s depend on the accelerators contents in each rubber component, while for simple mixing the vulcanization rate of blend is 0,075 lbf/s. So based on date from vulcanization curves the migration of accelerators in NR/EPDM blends may be evaluated. Key words: NR/EPDM blends, curative migration, vulcanization