Fecal Occult Blood Tests (FOBT) are routinely used to detect the blood released from GI lesions, including colorectal cancer. Colorectal cancer is the second most common serious cancer in the U.S. with 130,000 new cases and 60,000 deaths annually. Because it is slowly progressive with a long asymptomatic period, colorectal cancer provides an ideal opportunity for early detection and therapy. It is known that colorectal cancers frequently bleed, and that appropriate FOBT can be an important aid to early detection. Unfortunately, many clinical studies indicate that the most widely used commercial FOBT suffers from serious limitations in sensitivity and specificity. Proposed alternatives are no longer simple, rapid, inexpensive clinical tools. The proposed research is designed to produce the best commercial embodiment of a technically superior FOBT with significantly improved clinical performance while maintaining key user advantages.