The majority of intersection-related fatal crashes occur at rural through-stop intersections. At these intersections, sight restrictions caused by vertical and horizontal curves negatively affect a driver's ability to safely accept a gap in the traffic stream. Static advance warning signs are sometimes installed at these intersections to warn drivers on the main through approaches that an intersection is ahead. These warning signs appear to be ineffective. A new advance LED warning system was developed and deployed at a rural through-stop intersection that had limited intersection sight distance because of a severe vertical curve. The warning system actively detected vehicles on all approaches and activated LED blinker warning signs for the conflicting movements. The research project included an analysis of driver behavior at the intersection, obtained through video data, and a survey of local residents and frequent users of the intersection. This paper presents the results of the research conducted to assess the effectiveness of this new LED warning system.