Four new iridoids viz., plumeridoids A (1), B (2), and C (3) and epiplumeridoid C (4) were isolated from the stem bark of Plumeria rubra Linn. together with twenty-four known compounds viz., 1-(p-hydroxyphenyl)propan-1-one, isoplumericin, plumericin, dihydroplumericin, allamcin, fulvoplumerin, allamandin, plumieride, p-E-coumaric acid, 2,6-dimethoxy-p-benzoquinone, scopoletin, cycloart-25-en-3β,24-diol, 2,4,6-trimethoxyaniline, ajunolic acid, ursolic acid, oleanolic acid, β-amyrin acetate, betulinic acid, lupeol and its acetate, 2,3-dihydroxypropyl octacosanoate, glucoside of β-sitosterol, and a mixture of common sterols (stigmasterol and β-sitosterol). Their structures were determined by means of spectroscopic data including HREIMS, 1H NMR, 13C NMR, 2D NMR (HMQC, HMBC, NOESY) and by comparison with published data. All but one of thirteen tested compounds exhibited antifungal, antialgal, and/or antibacterial activities.