The miscibility of a ternary system of poly(3-hydroxybutyrate), poly(ethylene oxide) and polyepichlorohydrin was studied by differential scanning calorimetry. The three binary blend systems are individually miscible. All the ternary blends were found to be miscible as shown by the existence of a single glass transition temperature in each blend. The interaction parameters of the three binary pairs are of similar magnitude and do not lead to a "Delta chi" effect.