Human- Computer Interaction (HCI) systems are designed for disabled people who are unable to move or control any parts of their bodies except for their eyes. The idea behind our proposed system is detecting eye blink feature from a video with a high degree of accuracy. Our proposed system is considered as an alternative input modality enables people with severe disabilities form communicate with the computer. Our proposed system uses Viola Jones to detect the face and eye regions. Our proposed system is based on two steps for determining the state of the eye (being open or closed): The first step is splitting the eye region horizontally into two equal parts. Then find the difference between the number of black pixels of the first horizontal part in eye region and the number of black pixels of the second horizontal part in the eye region. The second step is applied only in the first horizontal part of the eye region by finding the ratio of black pixels to white pixels in this part, and this step added to ensure accurate results. The experimental results have proven that the proposed system detection accuracy is very efficient on the recorded cam videos and accurately detects eye blinks without any restriction on the background. The proposed system is very easy to configure and use. It is totally non-intrusive and it only requires one low-cost web camera and computer.