A screening program was conducted to find microorganisms that modify the synthetic cannabinoid nabilone. After purification, the products from three cultures were analyzed by spectral methods to determine their chemical structures. An optically active 9S-hydroxy-6aR,10aR-trans cannabinoid was isolated from a culture of an unidentified soil bacterium designated A24007. From Bacillus cereus cultures were isolated a 9S,6'-dihydroxy-6aR,10aR-trans cannabinoid, a 9S-hydroxy-6'-keto-6aR,10aR-trans cannabinoid, a 9-keto-6'-hydroxy-6aS,10aS-trans cannabinoid, and a 6',9-diketo-6aS,10aS-trans cannabinoid. All of these products were optically active, as was a 9S-hydroxy-6aS,10AS-trans cannabinoid also isolated from B. cereus cultures. A series of acidic products were isolated from cultures of Nocardia salmonicolor. All of these products contained a carboxylic acid group at the terminal end of three-position alkyl side chains having varying numbers of carbon atoms. Two of the acidic products contained a 9-keto group, whereas all other carboxylic acid products were 9-hydroxy cannabinoids. The array of products obtained from incubation of nabilone indicates the usefulness of microbial transformations in the preparation of new cannabinoids.