Further studies on the seeds of Annona cherimolia have led to the isolation of two pairs of Annonaceous acetogenins, a mixture of epimers of annomolon A (1) and 34-epi-annomolon A (1'), and a mixture of epimers of annomolon B (2) and 34-epi-annomolon B (2'), containing a rare gamma-hydroxymethyl-gamma-lactone moiety and a carbonyl group. Their structures were elucidated on the basis of spectroscopic and chemical methods, and their absolute stereochemistry was solved by preparing their respective per-Mosher ester derivatives. These acetogenins showed substantial cytotoxicity, comparable to that of adriamycin, against a human pancreatic tumor cell line (MIA PaCa-2).