A new Schiff base from the condensation of 5,6-diamino-1,3-dimethyluracil with 5-methylthiophene-2-carboxaldehyde was synthesized. The compound was characterized by spectral data (UV–Vis, IR, 1H NMR, fluorescence, MS). Ethanolic solutions of the Schiff base exhibit a strong fluorescence emission at 385 nm (kex= 341 nm), and have been employed as a ‘‘turn-off’’ fluorescent probe for selective detection of Ag+ ,Cu 2+ and Fe3+ ions in presence of other cations such as Na+ ,K+ ,Ca2+ and Mg2+ ions abundant in natural water. The interaction between the tested compound and copper, silver or iron ions is associated with a significant fluorescence decrease, showing detection limits of 2.1–14.2 ppb. Under optimal conditions, the developed sensor was successfully employed to determine Ag+, Cu2+ and Fe3+ ions in real samples and proved to be selective and sensitive