The mol-ecule of O-acetyl-swietenolide, C(29)H(36)O(9), isolated from the seeds of Swietenia macrophylla, features four six-membered rings connected together in the shape of a bowl; one of the inner rings adopts a twisted chair conformation owing to the C=C double bond. The furyl substitutent is connected to an outer ring, and it points away from the bowl cavity. The hy-droxy group is connected to a carbonyl O atom of an adjacent mol-ecule by an O-H⋯O hydrogen bond, generating a chain running along the b axis.