Pyrimidines are one of the most important class of heterocyclic compounds with a variety of biological activities. Keeping this in view, it was proposed to synthesize some novel pyrimidines from chalcones. The condensation of chalcones of 4'-piperzine acetophenone with guanidine hydrochloride gives pyrimidines. The structures of the synthesized compounds RCP1-5 were assigned on the basis of elemental analysis, IR and 1H NMR spectroscopy data. These compounds were also screened for their anti-histamine activity. The recorded % of histamine inhibition showed significant anti-histamine activity, when compared with standard antihistamine drug mepiramine.