Unexplained Mysteries is an American documentary television series that originally aired in syndication from 2003 to 2004 for a single season. The show deals with eyewitness accounts of paranormal activity, especially aliens, UFOs, and ghosts; almost all of them are rehashed reports from the series Sightings and Paranormal Borderline.

Unexplained Mysteries was a syndicated show and had a one-hour runtime. Jonathan David Cook was the show's host. Paramount Domestic Television produced the show. In addition to creating original footage for each Unexplained Mysteries episode, Paramount included numerous clips from Sightings, a show that had premiered on Fox in April 1992 and was syndicated between September 1994 and September 1996.

The program had 97% national coverage via 217 markets in 2003. John Nogawski, the president of Paramount Domestic Television, said in 2003 that the show was profitable. Nielsen Media Research said that on October 26, 2003, the show had 1.5 "national household rating". In 2004, Paramount renewed the program for its second season with a distribution reaching 80% of national markets. Unexplained Mysteries was syndicated between September 2003 and May 2004.