15Mo3 type steel samples were subjected to creep loading at 550&DEG; C in order to investigate the development of microstructure and the effect of the carbides on the creep process. Electron microscopic observations have shown that relatively small subgrains are formed up to the secondary stage of creep deformation. As the creep progresses, due to the growth of carbides, the average distance between the carbides is increased. This increased the mean free path of moving dislocations, in turn the size of the subgrain is also increased. This microstructural change is also verified by EBSD technique which shows the variation of the configuration of grain boundaries.