Intention of this work is the production and characterisation of highly filled films with a thermoplastic polyester matrix. Base materials for the practical work are a traditional aromatic polyester, PET 8200, a biological degradable polyester Biomax 4024 and two sorts of chalk, Omyacarb 2TSL and Omyafilm 707OG. At first, in order to find out the max-feasible filler content, compounds based on PET 8200 with different amounts of chalk are produced. These blends are then processed to a first set of sample films. The characteristics of these films lead to a new assessment of the optimum amount of filler and the production of a second series of films based on Biomax 4024. The compounds are characterized by means of loss on ignition experiments, highpressure- capillary-rheometry, heat conductivity measurements, light optical microscopy and differential scanning calorimetry (DSC). The films are examined using tensile tests, scanning electron microscopy, DSC and regarding to their thickness distribution. The rheological characteristics of mixtures based on PET 8200 strongly depend on the type and amount of chalk. On the other hand, compounds based on Biomax 4024, are rather unaffected of that. However the mechanical properties of the films based on the two polymer systems are strongly influenced by the amount of filler.