In many countries addition of sugar to the grape must for increasing the alcohol concentration is autorized by regulation. This addition must be supervised by a priori and a posteriori controls. The saccharose from sugar beet contrains 100 mg/kg of betain, which can be determined in wine after purification by ion exchange and gas chromatography of a decomposition product of its butylester. Methyl betaine has been used as internal standard to improve the method. The natural wine contains low quantity of betaine. For this reason it is impossible to detect an addition of sugar lower than that corresponding to 2 degrees alcohol. The other methods (13C content of ethanol, polyosides contained as impurity in sugar) seem to present the same limitation.