A binary poly(L-lactide)/poly(epsilon-caprolactone) (PLLA/PCL)(a) (70/30 w/w) blend and a ternary PLLA/PCL/PLLA-PCL-PLLA blend of the same composition which contains 4 wt.-% of a triblock PLLA-PCL-PLLA copolyester as compatibilizing agent were prepared by melt mixing at 200 degrees C. Investigation of the thermal and mechanical properties of the blends and scanning electron microscopy of their fracture surfaces showed in the case of the ternary blend a better state of dispersion of PCL in the PLLA matrix and an improved toughness.