IntroductionRemoval of extractives increases the shrinkage and swelling of wood (Nearn 1955, Salamon and Kozak 1968, Cooper 1974, Taylor 1974). The effect of progressive extraction on the above properties has not been investigated much. In oak (Quercus conferta L.), a forest species rich in extractives, the shrinkage progressively increased with progressive extraction (Voulgaridis et al. 1980). In black locust (Robinia pseudoacacia L.), much of the main-stem volume is comprised of heartwood, characterized by the presence of dark yellow-brown extractives. While the extractives of black locust give the heartwood its distinctive color and decay resistance, they comprise only 6.2 to 8.3% of the dry weight of the main stem (Stringer 1992). Hot-water extractives range from 5.2 to 8.6% (Hart 1968, So et al. 1980). The present study was primarily undertaken to determine whether the progressive removal of hot-water extractives affects the radial and tangential shrinkage of black locust heartwood.