The alkaloids present in the stem of three species of genus Neobuxbaumia Backeb. (Cactaceae), N. multiareolata (E.Y. Dawson) Bravo, Sheinvar & Sanchez-Mej., N. scoparia (Poselger) Backeb. and N. tetetzo ((J.M. Coup.) Backeb., were screened by gas chromatography-mass sepectrometry (GC-MS). In the three species analyzed the following tetrahydro-isoquinolines were identified: anhalidine, carnegine. and salsolidine, all in trace quantities. This paper is the. first record of alkaloids in N. multiareolata; N. scoparia and N. tetetzo. (C) 2002 Elsevier Science Ltd. All rights reserved.