Telltale rodent trap for trapping rodents in interior walls, ceilings and similar spaces including a baited and set spring-loaded trap attached to a base plate that can pass through a wall or ceiling opening to be exposed to interior spaces frequented by rodents. A cover plate having a telltale aperture fits over the opening. Flexible wings are attached to the rear of the base plate and can fold towards and pass through said opening and thereafter unfold to hold the trap in place. A telltale strip is attached at one end to a trap arm adapted to pivot between a first position when the trap is set and a second position when the trap is sprung. The other end of the telltale is inserted between the cover and base plates and is visible in the telltale aperture of the cover plate. When the trap is sprung, the trap arm pulls the telltale so it is no longer visible in the telltale aperture indicating that a rodent has been trapped and the trap assembly should be removed and reset.