Brian Weiss is a psychiatrist who started treating a young woman with a number of fears. He was having trouble finding the causes of those fears, and eventually resorted to hypnosis. Even though he uncovered some potential causes from when she was three years old, her symptoms did not improve. So in the next session he told her, "Go back to the time from which your symptoms arise." She started describing a scene from 1863 B.C.
The book describes many of her past lives, as well as words from "spirit masters" when she is between lives. The author tries to be scientific but comes to strongly believe in reincarnation due to the experience described in this book. The patient was not just cured of her fears, but became beautiful and radiant due to this therapy.
Very interesting and definitely worth reading, and if you can do so with an open mind, all the better. It is an easy read. The descriptions of "how it all works" are consistent with the three books by Robert Monroe (also, highly recommend: I will review those soon), which in my mind gives it further credibility.
Amazon JP (English)
Amazon JP (Japanese translation: 前世療法—米国精神科医が体験した輪廻転生の神秘)