TPU and chlorinated thermoplastic polyurethane (CTPU) were synthesized by using a two-step solution polymerization technique from poly(caprolactone) (CAPA), 4’,4-diphenyl-methanediisocyanate (MDI) and 1,2-propandiol(PD) or 3-chloro-1,2-propandiol(CPD) for CTPU, respectively. TPU and CTPU were blended with styrene/acrylonitriles (SANs) with a different amount of acrylonitrile within the entire compositional range. The blends were prepared as films from 15 wt% solution in dimethylformamide (DMF). The thermal properties of TPU, CTPU, SANs and their blends, as well as the influence of the amount of acrylonitrile (AN) component in SANs on the thermal behavior of blends, were studied by differential scanning calorimetry (DSC). The Flory-Huggins interaction parameter (chi(12)) was estimated.