The phase behaviour of ternary polymer blends consisting of poly(epsilon-caprolactone) (PCL), poly(hydroxy ether of bisphenol A) (Phenoxy) and poly(styrene-co-acrylonitrile) with an acrylonitrile content of 15 wt% (SAN15) was examined by means of visual observations, light transmission measurements, differential scanning calorimetry (d.s.c.) and dynamic mechanical thermal analysis (d.m.t.a.). The influence of the blend composition, the crystallization temperature, the crystallization time and the d.s.c. scanning rate on the crystallization and the melting behaviour of the blends was investigated.