From the stem-bark of Juglans mandshurica, two new naphthalenyl glucopyranosides, 1, 4, 8-trihydroxy-nahthalene 1-O-[α-L-arabinofuranosyl-(1→6)-β-D-glucopyranoside] (1) and 1, 4, 8-trihydroxynaphthalene 1-O-β-D[6'-O-(3", 5"-dihydroxy-4"-methoxybenzoyl)]glucopyranoside (4), and two new α-tetralonyl glucopyranosides, 4α, 5, 8-trihydroxy-α-tetralone 5-O-β-D-[6'-O-(3", 5"-dihydroxy-4"-methoxybenzoyl)glucopyranoside (7) and 4α, 5, 8-trihydroxy-α-tetralone 5-O-β-D-[6'-O-(3", 4", 5"-trihydroxybenzoyl)glucopyranoside (8), were isolated together with three known naphthalenyl glucopyranosides (2, 3 and 5), one α-tetralonyl glucopyranoside (6), four flavonoids (9-12), and two gaalloyl glucopyranosides (13, 14).Amongst the isolated compounds, 1, 2, 6-trigalloylglucopyranose (13) and 1, 2, 3, 6-tertagalloylglucopyranose (14) exhibited the most potent inhibition of reverse transcriptase (RT) activity with IC₅₀ values of 0.067 and 0.040 μM, respectively, while the latter compound also inhibited ribonuclease H (RNase H) activity with an IC₅₀ of 39 μM, comparable in potency to illimaquinone used as a positive contorl. 1, 4, 8-Trihydroxy-naphthalene 1-O-β-D-glucopyranoside (2), 1, 4, 8-trihydroxynaphthalene 1-O-β-D-[6'-O-(4"-hydroxy-3", 5"-dimethoxybenzoyl)]glu-copyranoside (3) and 8 showed moderate inhibition against both enyzme activities, and inhibitory potency of 2 against RNase H activity (IC₅₀=156 μM) was slightly greater than that against the RT activity (IC₅₀=290 μM).The inhibitory potencies of 4α, 5, 8-trihydroxy-α-tetralone 5-O-β-D-[6'-O-4"-hydroxy-3", 5"-dimethoxybenzoyl)] glucopyranoside (6), 7 and 8 against RT activity increased accompanied by an increase in the number of free hydroxyls on the galloyl residues, as represented by the IC₅₀ values of >500, 330 and 5.8 μM, respectively.