Four triterpenes, three lupanes, and a germanicane were isolated from Machaerocereus eruca. The germanicane derivative (1) was determined to be 3 beta,19 alpha-dihydroxygermanican-28-oic acid and named machaeroceric acid. The three new lupane derivatives were identified as 21-ketobetulinic acid (2), 16 beta-hydroxybetulinic acid (3), and 22 beta-hydroxystellatogenin (4), respectively, on the basis of their spectroscopic data.