The crystallization in polyethylene oxide/polymethyl methacrylate (PEO/PMMA) blends was investigated with respect to composition and different casting solvents. Sharp changes in the intensities of the major reflections (120 and 112/004 from PEO) were observed in their X-ray diffraction scans when these blends were cast from different solvents. Large deviations were noted in the crystallinity values as well as the intensities of the peaks from those expected from simple rules of mixture or dilution law. The various results could be explained on the basis of restricted growth of the PEO crystallites along certain directions in the presence of PMMA. Copyright © 1996 Elsevier Science Ltd.