Panel manufacturers, with the help of resin producers, R&D laboratories such as Forintek and their own ingeniosity have succeeded in constantly improving OSB performance. It is thus expected that the OSB share of the composite market will continue to increase as it offers an interesting alternative to other wood and non-wood panels. However, some properties such as surface quality and dimensional stability still need to be improved to help OSB in capturing new markets. Following an industry recommendation, Forintek initiated a project to develop OSB/waferboard panels with superior properties that could be used for applications other than sheathing. The stylus equipment, needed to measure the surface of OSb samples subjected to various moisture treatment, was purchased. Preliminary screening work indicated that the surface smoothness of OSB underlayment could be improved by filling the voids with a high solids filler/coating latex, by addition of fine wood particles which pass through a 850 um screen opening or by the addition of wood or paper fibers onto the surface of OSB. One filler/coating identified in this preliminary study may be acceptable for underlayment applications. The best results, for samples conditioned under severe moisture conditions, were obtained with the paper fiber or wood fiber bonded onto OSB surface.