It is well established that part of starch is resistant to human amylases and escapes undigested to large bowel. This fraction of starch is resistant starch. Recent studies have shown that resistant starch may be a substrate for bacterial flora of the colon and serves as prebiotic. Short chain fatty acids (SCFA) produced by colonic fermentation of resistant starch may have impact on colonic function and health of humans. This paper summarises current knowledge on properties and health impact of resistant starch.