The fluorimetric determination of gallium at the nanogram level, based on the formation of a fluorescent complex between Ga^III and salicylaldehyde carbohydrazone (SACH), is proposed. With excitation at 360 nm, the chelate has an emission maximum at 450 nm. The reaction is carried out at pH 2.4–3.1 in aqueous ethanolic medium (60%V/V ethanol). The influence of the reaction variables is discussed. The detection limit is 0.5 ng ml^–1 and the range of application is 1.5–60 ng ml^–1. The relative error of the method is 3%. The proposed method has been applied to the determination of gallium in biological samples and alloys.