The structure of the new diterpene alkaloid acofine, isolated from tubers of Aconitum karakolicum, has been shown by the x-ray structural method (diffractometer, CuKα, 1250 reflections, direct method, R=0.071). The IR, mass, and PMR spectrum of acofine and its monoacetate are considered. Acofine is the first chlorine-containing diterpene alkaloid, and also the first alkaloid of the napelline type with a 15,16β-acetonide group. © 1993 Plenum Publishing Corporation.