Light and electron microscopy of immobilized system of theClaviceps sp.strain in Ca-alginate reveal some peculiarities in the growth and morphology of the cells as compared to the free ones. The immobilized cells develop mainly in the surface and subsurface layer of the alginate beads. Cells of differing physiological state are observed. Higher is the number of the sclerotia-like cells and of the arthrosporoid-like structures.