Eleven new mexicanolide-type limonoids, swietmanins A-I (1-4, 7-11), 2-hydroxy-3-O-isobutyrylproceranolide (5), 2-hydroxy-3-O-benzoylproceranolide (6), and a new andirobin-type limonoid, swietmanin J (12), together with 19 known compounds were isolated from the fruits of Swietenia mahagoni. Their