The extract of Ongael [leaves of Phaleria cumingii (MEISN.) F. VILL.], a Palauan medicinal herb, enhanced an in vitro phagocytic activity of mouse macrophages RAW 264.7 cells (RAW 264.7). Activity-guided fractionation of the Ongael extract by the in vitro phagocytosis assay using RAW 264.7 led to the isolation of a mixture of acylglucosylsterols (1) as an active constituent along with other inactive constituents, tetracosanol and mangiferin. On the basis of chemical modifications and spectral analyses, the compound 1 was deduced to be a mixture of the known 3-O-(6-O-acyl-beta-D-glucosyl)-beta-sitosterols, the acyl moiety being mainly palmitoyl (57%), oleoyl (12%) and alpha-linolenoyl (12%) with small amount of stearoyl (7%) and linoleoyl (4%).