Nanolaminates and bilayers of BN/AlN on Si were deposited using a reactive DC magnetron sputtering technique in a dual-cathode system. In the BN/AlN bilayers, there was little effect of the AlN thickness as a buffer layer on the crystallinity of the BN layer. A series of BN/AlN nanolaminates with periods (A) from 2.2 to 80 nm was produced by varying the rotation speed of the sample holder disc. At the periods thicker than 20 nm, the nanolaminates primarily consisted of sp(3)-bonded BN and w-AlN layers. For periods below 3.4 nm, the BN and AlN layers were intermixed and apparent wurtzite-AlBN phase was formed in the interfaces. Transparent and intact BN/AlN nanolaminates with thickness over 5 mum and with hardness over 33 GPa were obtained. The hardness of the nanolaminates was related to the structural characteristics obtained from XRD and FTIR results.