AbstractAn investigation was undertaken on the application of the three‐dimensional solubility parameter method to predict miscibility of polyblends. The three‐dimensional method attempts to account for the combined effects of dispersion, polar, and hydrogen bonding interactions between molecules. This study focused mainly on the miscibility of blends of poly(vinyl chloride) (PVC) with homopolymers as well as with copolymers. The three components of solubility parameters were calculated from the group contributions of the structural units of the polymers. By comparing the parameters of different PVC blends in two categories, PVC/homopolymer and PVC/copolymer blends, the miscibility trend of PVC blends was revealed. The three‐dimensional solubility parameter approach successfully predicted the miscibility of several homopolymers. For copolymers, the chance of miscibility was increased because of the ability to adjust the solubility parameter through composition. This was reflected in a smaller distance between the solubility parameter of copolymer and that of PVC. Experimental results reported in the literature confirmed this conclusion. © 1993 John Wiley&Son