AbstractBufalin (1) was transformed to 7β‐hydroxybufalin (2) by an aqueous suspension of the mycelium of Absidia orchidis VUILL. (HAGEM.). Incubation of resibuforgenin (9) under the same conditions yielded 12α‐hydroxyresibufogenin (7) and, under changed conditions, another monohydroxylated derivative which possesses most likely the structure of 7β‐hydroxyresibufogenin (10). The corresponding cardenolide 3‐O‐acetyl‐14β, 15β‐epoxy‐14‐anhydro‐digitoxigenin (17) gave both the 7β‐ and the 12α‐monohydroxylated derivatives 18 and 22 and another monohydroxylated product 21 of unknown structure. All microbial transformation products are new.