Abstract: For each of the plantation-and natural-grown Korean Pines(Pinus koraiensis Sieb. Et Zucc.)four sample trees had been selected in this study.In first place,results for comparison of the anatomical features and physico-mechanical properties of the fast- (plantation-)(a)and slow-grown(natural-grown)(b)Korean Pine timbers have been shown.Secondly,with the plantation-grown material the writers have proven the Turn- bull's hypothesis that the increase in density of coniferous wood from the pith outwards is determined solely by age from the pith and has nothing to do with ring-width.These conclusions may be indicated as follows: 1.In diameter growth,(a)grows 4 times faster more than(b);in length growth, about 3 times,(a)vs.(b).Tracheids in(a)are longer(ca.31%)and larger(early- wood,11%;latewood,28%)than in(b).Latewood percentage and density of(a)are 28% and 2% lower respectively than(b);but strength properties have been shown about the same.In case of comparison on their corresponding rings,(a)is generally heavier and stronger than(b).Thus the fact that the rapid growth,high yields and good qualities of Korean Pine timbers could be reached by a proper silvicultural treatment has been proven. 2.From pith outwards,tracheid length and growth ring width decrease more ap- parently;except the first few years,the variations of the diameter of tracheids,per- centage of both latewood and cell wall are small and fluctuate irregularly.The density and strength of(a)reach the maximum value at 9th to 18th growth rings;in(b),at 30th to 70th growth rings. 3.Upwards from height at 1.3—11.3 meters within a growth ring or scope of growth rings,tracheid length increases,but latewood percentage,density and so forth decrease.The strength properties except(b)the maximum value of which occurs at height of 5.3—7.3 meters and tends to increase outwards before 50 rings from pith,de- crease upwards. 4.The number of resin canals is in direct proportion to the width of growth rings. They are mostly distributed in the summerwood bands or(and)the transitional regions of early-and summerwood.