The lost sims of TOL CSI refer to three Star Trek chat role-plays that served in the Trek Online CompuServe Division (TOL CSI) during the summer of 1997. The three sims were launched in July of that year to serve the European time zone; all three sims were manned and simmed at least once, but were spread thin, and following a school slump were canceled that autumn.

The records of the sims, including their names, have been lost. The names officially entered into the Trek Online sim register on their behalf - the USS Rome, USS Truman, and USS Europa - are based on speculation and memory.