Exposure techniques have now been used in the treatment of anxiety disorders for several decades. Although such techniques are a dominant feature of current therapies for disorders such as posttraumatic stress disorder and acute stress disorder, examination of their relative merits has been less studied. The purpose of this review is to suggest the usefulness of in vivo flooding in the treatment of posttraumatic stress. We discuss the relevant exposure literature by briefly examining the efficacy of these techniques in the treatment of anxiety. The theoretical and methodological limitations of investigations to date of exposure methods that have been used in posttraumatic stress treatment studies are then reviewed. We highlight the fact that in vivo flooding, an exposure technique that has been used to treat some anxiety-based disorders, has received scant clinical and research attention as a treatment for posttraumatic stress. A case is made for further study of in vivo flooding in the treatment of posttraumatic stress.