An original simple and patent-free method for synthesis of the active pharmaceutical ingredient of aripiprazole was developed. The method is based on condensation of 7-(4-bromobutoxy)-1,2-dihydroquinoline-2-on with 4-(2,3-dichlorophenyi)piperazine in EtOH at b.p. in presence of Na2CO3 for 6 h. The resulting aripiprazole solvate or hydrate (yield 85-90%, purity above 99.301.) meets the resp. quality requirements.