Two new 7,8-secolignans, marphenols A and B (1 and 2, resp.), together with a known related derivative, 7,8-secoholostylone B (3), were isolated from the stems of Schisandra wilsoniana. The structures of 1 and 2 were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. The anti-HIV-1 activities of 1-3 were evaluated. Compound 1 inhibited HIV-1(IIIB)-induced syncytia formation with an EC(50) value of 0.55 μg ml(-1). It reduced p24 antigen expression in acutely HIV-1(IIIB)-infected C8166 cells and primary isolate HIV-1(TC-2)-infected peripheral blood mononuclear cells (PBMCs), with EC(50) values of 3.34 and 0.52 μg ml(-1), respectively. It showed no effects on the HIV-1(IIIB) replication in chronically infected H9 cells as well as fusion inhibition.