This paper presents an image-based lane departure warning (LDW) system using the Lucas-Kanada (L-K) optical flow and the Hough transform methods. Based on the status of the vehicle deviating from its heading lane, the method integrates both techniques to establish an operation algorithm to determine whether a warning signal should be issued. The L-K optical flow tracking is used when the lane boundaries cannot be detected, while the lane detection technique is used when they become available. Even though both techniques are used in the system, only one method is activated at any given time because each technique has its own advantages and also disadvantages. The image-based LDW system was road tested on rural highways and this paper briefly presents the system implementation and test results.