Poly(lactic acid), frequently referred to as PLA is a polymer which gains increasing interest in both science and industry as it is produced from renewable biological resources. Although is biodegradable and thus compostable it is lacking from some short-comings, e.g. processing operations are limited by the polymers’ low melt strength, while its brittle fracture behavior hinders application. The first point is related to the molecules’ linear architecture. As well known for PET chain extenders can be used to tailor molar mass distribution (MMD) as well as the degree of long-chain branching and so to increase melt strength. PLA was reactively processed together with a commercial chain extender at various concentrations in a kneader and in a twin screw extruder. All materials were dried under vacuum prior to any processing and/or characterization to a water content below 100 ppm to avoid (hydrolytic)degradation. MMD and(possible)long-chain branching were determined by triple detection SEC in HFIP. All samples for rheological tests were prepared by compression molding. Rheological measurements in shear end elongation were performed in nitrogen atmosphere by means of a rotational rheometer equipped with an elongational test fixture. All rheological test were conducted on time scales assuring thermal stability. Triple detector GPC proves an increase in molar mass, a broadening of the molas mass distribution, as well the formation of LCB. All findings have been confirmed by rheological measurements showing an increase in zero shear viscosity together with improved shear thinning behaviour. LCB formation was further confirmed by a pronounced strain-hardening behaviour in elongational flow. The rheological behaviour suggests a branch-on-branch archictecture of the LCB-PLA. Extruded cast film shows less neck-in with the addition of chain extender and a more uniform film thickness as expected due to strain hardening.