This study was to diagnose the ontogenetic ability of drought tolerance in trees, and was to investigate the seasonal changes in tissue-water relations parameters, πo, πp, Emax, Ns/DW, Vo/Ws and RWC(tlp) obtained from P-V curves on the Pinus koraiensis and Abies holophylla shoots. The results obtained are as follows; 1) Seasonal changes of original osmotic pressure at maximum turgot, πo, were -1.2 to -1.6 ㎫ in Pinus koraiensis and -1.4 to -1.7 ㎫ in Abies holophylla. 2) Seasonal changes of osmotic pressure at incipient plasmolysis, πp, were -1.8 to -2.1 ㎫ in Pinus koraiensis and -I .6 to -2.1 ㎫ in Abies holophylla. 3) Seasonal changes of relative water content at incipient plasmolysis, RWC_(tlp) were 70 to 77% in Pinus koraiensis and 69 to 85% in Abies holophylla. 4) Seasonal changes of maximum bulk modulus of elasticity at maximum hydration, Emax, wE:re 2.2 to 6.3 ㎫ in Pinus koraiensis and 3.1 to 7.9 ㎫ in Abies holophylla. 5) Seasonal changes of number of osmoles of solute in symplasm versus dry weight, Ns/DW, were 0.5 to 1.3 in Pinus koraiensis and 0.3 to 1.0 in Abies holophylla. 6) Seasonal changes of original osmotic water volume versus total water volume (symplasmic and apoplastic water), Vo/Ws, were 55 to 65%r in Pinus koraiensis and 40 to 65% in Abies holophylla. Consequently, as the comparative values of πo, πp, Emax, Ns/DW, Vo/Ws, and RWC_(tlp) it might be suggested that Abies holophylla shoot could have more or less a greater ability of drought tolerance as compared with Pinus koraiensis shoot.