The fractionation work of the aerial parts of Senecio atacamensis Phil, afforded, in addition to the already known 6 beta - hydroxyeremophilenolide, a new sesquiterpene lactone 6 beta - hydroxy - 8 alpha - methoxyeremophil - 1(10),7(11) - dien - 8 beta ,12 olide. The structures were established by spectral data, in particular 2D NMR (DEPT, DQF-COSY, HMQC, HMBC and ROESY).