Abstarct: The catalyst-free four-component reaction of aldehydes, malononitrile, barbituric acids and ammonium acetate in magnetized water, at 90 oC ¬¬¬¬afforded to pyrido[2,3-d]pyrimidine derivatives in good-to-high yields. Further more this method offers numerous advantages including catalyst-free, short reaction times and good-to-high yields of products.