Assorted information sources have been used to estimate the wood volume in the national or regional forest inventory covering the large areas. The tops of the se are fıeldwork, aerial photos, and satellite data. Although more detailed and reliable information is attained by fıeldwork, it is very expensive and time-consuming. Aerial photos have been used to reduce the inventory cost by means of decreasing the terrestrial works for a long time. With the beginning of satellite data use in the national forest inventory studies during the last decade, multi-phased sampling methods have been employed to combine fıeldwork, aerial photos, and satellite data. In this paper, multi-phased sampling methods were explained basing on the literature conceming the subject. Using possibilities of these methods in the national forest inventory studies those are inevitable for our country were investigated.