Summary form only given. Rapid transaction undo recovery is important for many transaction processing applications. The Wu-Fuchs method is efficient in that it eliminates the need for I/O in undoing disk updates on a transaction abort. However, it is dependent on maintaining a list of aborted transaction ID's which must be searched every time a database page is read. This can become a performance bottleneck especially if the abort list becomes very long. Although Wu and Fuchs propose a low-priority process to run in the background and prune the list of extinct transactions, in a heavily-utilized system such a low-priority process may not be scheduled frequently enough to be effective. We propose a method for systematically pruning the abort list of transaction ID's as soon as they become obsolete. Our method eliminates the dependence on a cleanup process and adds little processing overhead.