Technical Abstract: Sugar losses have been a major concern of many sugar industries around the world for decades, and have recently become a focus in improved process efficiency attempts in countries that did not previously focus on them, for example, Brazil. Emphasis has usually been on minimizing sucrose losses but, with more processing of sugarcane for fuel alcohol production there is an increasing emphasis on also minimizing the losses of the fermentable sugars glucose and fructose (invert) to improve alcohol yields. Sucrose is most stable ~pH 8.3, whereas glucose and fructose are most stable under severe acid conditions pH 3-4, thus balancing the minimization of both sucrose and invert sugars serves as a real challenge to sugar technologists. Sucrose under sugarcane processing conditions is often susceptible to acid hydrolysis or inversion reactions. It is well known that sucrose acid hydrolysis is affected by factory pH, temperature, oBrix and retention time conditions, but it is less known that invert sugars themselves and salts can catalyze and accelerate sucrose hydrolysis. The effects of invert and salts are becoming an increasingly greater problem with the increasing worldwide change to green (unburnt) sugarcane from burnt sugarcane, because the greater deliveries of green trash, i.e., leaves and tops, to factories has meant delivery of higher amounts of invert and salts. This paper reviews the reasons for the chemical destruction of sucrose, glucose and fructose during the processing of sugarcane for the production of raw sugar and fuel alcohol. Industrial examples are highlighted as well as discussions on how to measure, minimize, and control chemical losses.