Antibacterial activity and biotoxicity against Artemia salina of chloroform and alcohol extracts and isolated products from four plants used in ethnomedicine in northern Chile is reported. Nine compounds already identified were isolated from aerial parts of Artemisia copa Phil., Acantholippia punensis Botta, Ephedra andina Poepp. ex C. A . Mey and Haplopappus rigidus Phil : 3,5 ­ dihydroxy ­ 6, 7, 3', 4' ­ tetramethoxyflavone, lupeol, beta ­ amyrine , beta ­ sitosterol, ephedrine, 2 ­ ethylhexanol phthalate , 18 ­ acetoxy ­ cis ­ cleroda ­ 3,13 Z ­ dien ­ 15 ­ oic acid, 5,4' ­ dihydroxy ­7­ methoxyflavanone and 3,5,7 ­ trihydroxy ­ 6, 4' ­ dimethoxyflavone