Two new bioactive Annonaceous acetogenins, annoglaxin (1) and 27-hydroxybullatacin (2), have been isolated from the fractionated ethanolic extracts of the leaves of Annona glabra, directing the fractionation with the brine shrimp lethality test (BST). The structures of 1 and 2 were elucidated on the basis of spectroscopic and chemical methods, and the absolute stereochemistries were determined by the advanced Mosher ester method. 1 presents unusual features of an OH at C-8 and a carbonyl at C-12 and, while less potent than 2, shows interesting selectivity for the human breast carcinoma (MCF-7) cell line. Compound 2 was at least 100 000 times more potent than adriamycin against the human kidney carcinoma (A-498), prostate carcinoma (PC-3), and pancreatic carcinoma (PACA-2) cell lines in our panel of six human solid tumor cell lines.