1-n-Butyl-3-methylimidazolium tetrachloroindate (BMI center dot InCl4) was found to be an efficient catalyst for the synthesis of 3,4-dihydropyrimidinones in high yields under solvent-free conditions. The recovered ionic liquid phase could be reused for several runs without significant loss in activity. In addition, BMI center dot InCl4 is more stable toward water and air than its analogous 1-n-butyl-3-methylimidazolium tetrachloroaluminate and, hence, easier to handle.