Aiming at development of completely biodegradable composite materials based on locally available low-cost bamboo flour (BF) as filler, structure properties correlations in aliphaticaromatic copolyester/BF composites fabricated by melt mixing have been studied by means of different techniques such as electron microscopy, X-ray diffraction, tensile testing, and thermogravimetric analysis (TGA). It has been demonstrated that the BF can be successfully incorporated homogeneously into the biodegradable polymeric matrix up to high content. The filler weakly adheres to the matrix as demonstrated by the pulling up of bamboo fibers on the electron micrographs and further attested by TGA. At high filler concentration, the polymer acts merely as binding material. The semicrystalline framework of the matrix polymer is hindered by the presence of the fibers, the structural changes being more pronounced at the surfaces than in the bulk, which indicates preferential segregation of the fibers toward the specimen surface. This opens new possibilities for a more detailed engineering of materials surfaces. The mechanical properties of the composites are suited for low-load-bearing applications. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers