Mo. Rev. Stat. § 534.300: Three years' possession a bar to the action.

The provisions of this chapter shall not extend to any person who has had the uninterrupted occupation or been in quiet possession of any lands or tenements for the space of three whole years together, immediately preceding the filing of the complaint, or who has continued three whole years in the peaceable possession after the time for which the premises were demised or let to him, or those under whom he claims, shall have expired.