A monoterpene-neolignan, piperitylmagnolol (1), was isolated from the stem bark of Magnolia officinalis, together with syringaresinol (2), caffeic acid (3), and sinapaldehyde (4). The isolated compounds were established on the basis of spectroscopic and physicochemical analyses including 1D- and 2D-NMR techniques, as well as on comparing the spectral data with those in the literature and of authentic samples. Compounds 1 - 4 were tested for their cytotoxic activity against the HeLa, K562, A549, and HCT116 cancer cell lines in vitro. Of the isolates, piperitylmagnolol (1) exhibited cytotoxic activity against the tested cancer cell lines with $IC_{50}$ values of 7.7 - 9.5 ${mu}g/ml$.