Concise and efficient domino [3+2+1] heterocyclization of isothiocyanates with aryl amidines has been established for the synthesis of 1,3,5-triazine derivatives. The multicomponent domino reaction (MDR, AB 2 type) is easy to perform simply by mixing inexpensive isothiocyanates and aryl amidines in the presence of NaOH under microwave heating. The present synthesis shows attractive properties such as concise one-pot conditions, short reaction periods (15–24min), and easy purifications. The resulting 1,3,5-triazine derivatives are important structural motifs in organic and medicinal research.