BN powders (with and without water) which have undergone low-energy ball-milling have been studied through X-ray diffraction, transmission electron microscopy, granulometry, electron energy loss (EELS) and IR spectroscopies. The main result is the formation of the orthorhombic and cubic high pressure phases of BN. A "turbostratic" behaviour of hexagonal BN has also been observed. As expected, the grain sizes decrease markedly. It is to be noticed that the presence of water induces some chemical reactions which are revealed through ammonia-like and nitride compounds scents. However, according to EELS measurements, the main transformations are structural ones.