CHEN JH, WANG SY, LIN CJ, CHIU CM & TSAI MJ. 2014. Evaluation of quality of Japanese cedar (Cryptomeria japonica) trees grown under different row thinning treatments. The effects of various row thinning treatments on the wood quality of Japanese cedar (Cryptomeria japonica) using non-destructive techniques were investigated. Differences between row thinning treatments were not statistically significant. The earlywood density (ED), latewood density (LD), minimum density in a ring (DMin), maximum density in a ring (DMax) and latewood percentage (LWP) were the most important predictors of ring density (RD) according to simple linear regressions. Compressive strength in the transverse direction increased from the pith outwards to certain points (about 11–24 years old) and then gradually decreased towards the bark. The ring width and earlywood width in the transverse direction changed irregularly from the pith outwards to the 4th ring, then gradually decreased towards the 25th ring and then slowly increased towards the bark. However, the RD and LWP in the transverse direction changed irregularly from the pith outwards to the 4thring, gradually increased towards the 25th ring and then decreased irregularly towards the bark.