An atom-efficient, catalyst-free and environmentally friendly approach towards the synthesis of 1,3,4-trisubstituted imidazolidines (4a–4p) through a multicomponent reaction involving monophenacyl anilines 1, aromatic amines 2 and formaldehyde 3 has been developed. The reaction proceeds in refluxing ethanol providing higher yields of the imidazolidines.