Three tetrahydro-11β(H)-santonins have been obtained by the hydrogenation of 11β(H)-santonin over palladised charcoal. Two of these tetrahydro-11β(H)-santonins were previously obtained by Clemo. They have now been shown to have a trans-a/b ring-fusion, by relating them to the stable trans-a/b ring-fused tetrahydrosantonin. A third tetrahydro-11β(H)-santonin (cis-a/b ring-fusion) and 1:2-dihydro-11β(H)-santonin