For the first time, the n-hexane extract from the dried stem bark of Cassia grandis L.f. was investigated, and one new fatty acid derivative, named casgraester A (1), was obtained, together with three known ones, 2,3-dihydroxypropyl 28-hydroxyoctacosanoate (2), 2,3-dihydroxypropyl octacosanoate (3), bis-(2,3-dihydroxypropyl)tetracosanedioate (4), three known triterpenoids, lupeol (5), betulinic acid (6), oleanolic acid (7), and three known steroids, β-sitosterol (8), 3-O-β-D-glucopyranosyl-β-sitosterol (9), and 3-O-β-D-glucopyranosylbrassicasterol (10). For the first time, compounds 2–4, 6, and 10 were reported from the genus Cassia, while compounds 5, 7, and 9 were found for the first time from this species. Their structures were elucidated by IR, HR-ICR-MS, ESI-MS/MS, and NMR experiments.