Moringa oleifera Lam. (Moringaceae), commonly known as the drumstick tree or the horseradish tree, is a shrub and small deciduous tree of 2.5 to 10 m height [1]. The leaves of the titled plant, as well as the flowers, roots, gums, fruits, and seeds, are extensively used for treating cardiovascular disease [2], liver disease [3], cancer [4], and hematologic, hepatic, and renal disease [5]. Compared to extensive medicinal studies, the limited phytochemical investigations report mainly the identification of glycosides and alkaloids such as 4-( -L-rhamnosyloxybenzylglucosinolate), niazimicin, niazirin, and moringine [6–9]. Breast cancer is a disease of humans and other mammals; while the overwhelming majority of cases in humans involve women, men can also develop breast cancer [10, 11]. MCF-7 and two other tumor cell lines account for more than two-thirds of all human breast cancer reported cases. Clinically, the number of doxorubicin-resistant MCF-7 adenocarcinoma (MCF-7/ADR) cases has grown, making traditional chemotherapy fail. In the preliminary trials performed by our group, the low-polarity fraction of the methanol extracts of the root barks of M. oleifera at 50 g/mL concentration displayed significant cytotoxicity against MCF-7/ADR tumor cell lines with an inhibition percentage of 56%. Therefore, in our continuing program aimed at the discovery of new anti-tumor drugs, M. oleifera was selected as the target, and in present study we wish to report the structural elucidation of compounds 1 and 2 and the cytotoxicity of some of these isolates towards the MCF-7/ADR adenocarcinoma cell lines. Air-dried and powdered root barks of M. oleifera were extracted with MeOH under reflux. The methanol extracts were purified using a combination of conventional chromatographic techniques. N-benzylcarbamic acid (1) and 4-( -L-rhamnopyranosyloxy)benzaldehyde (2), along with 25 known compounds, were identified, and comprehensive studies of their spectral and physical data were made. Compound 1 was isolated as a white powder with mp 244–245 C, and the HR-MS analytical data of 1 displayed a pseudomolecular ion peak at m/z 152.0736 corresponding to the molecular formula of C8H9NO2. The UV absorption maxima at 267 and 211 nm were characteristic of the existence of a benzenoid moiety [12]. The IR absorption bands at 3322 and 1621 cm–1 suggested the presence of hydroxyl and amide carbonyl groups, respectively. In the 1H NMR spectrum, a set of mutually coupled aromatic proton signals at 7.25–7.32 (5H, m) and a doublet signal at 4.36 (2H, J = 5.7 Hz, H-1 ) indicated the partial structure of the benzyl moiety. In addition, in the 13C NMR spectrum, the carbon signal at 158.0 (C-3 ) was characteristic of a carbamic acid group in compound 1, and another set of aromatic carbon signals at 139.0 (C-1), 128.7 (C-3, 5), and 127.4 (C-2, 6), 127.4 (C-4) confirmed the presence of a mono-substituted benzene basic structure. Thus, the chemical structure of 1 was established as N-benzylcarbamic acid. Although this compound had already been reported in the previous synthesis work [13], this is the first report from a natural source.