In this review we report on a method to modify mechanical performances of biocompatible matrices (polylactic acid, polycaprolactone and polyhydroxybutyrate) by reactive blending with polymethylmethacrylate. In a general approach the methacrylic monomer is polymerised in the presence of the biocompatible matrix in solution, in bulk or in suspension by means of peroxide initiators. In all the studied cases interpolymeric species are formed during polymerisation and blending, responsible of the change in mechanical properties, when compared to non reactive approach. All prepared blends were characterised by thermal, morphological, dynamic mechanical and mechanical analyses.