Asitrocin (1) and the mixture of (2,4)-cis- and trans-asitrocinones (2 and 3), new bioactive Annonaceous acetogenins, were isolated from the seeds of Asimina triloba by activity-directed fractionation using the brine shrimp lethality test. Asitrocin and the mixture of (2,4)-cis- and trans-asitrocinones have a configuration of erythro/trans/threo from C-15 to C-20, the mono-THF moiety with two flanking hydroxyl groups. The structures were determined by spectroscopic methods. These acetogenins showed potent bioactivities in the brine shrimp lethality test (BST) and among six human solid tumor cell lines with notable selectivity for the prostate (PC-3) and the pancreatic (MIA PaCa-2) cell lines at 10-100 times the potency of adriamycin.