2-Amino-5-(heteroarylmethylene)-1,3,4-oxadiazoles/thiadiazoles 7-10 were synthesized by cyclisation of 1-(heteroarylacetyl)semicarbazides/thiosemicarbazides 3-6. 5-(2'-Heteroarylmethylene-5'-aminomethylene-1',3,'4'- oxadiazol-2'-yl/thiadiazol-2'-yl)-2-oxo/thiobarbituric acids 11-18 were synthesized by condensation of compounds 7-10 at the 5th position of 2-oxo/thiobarbituric acids. The newly synthesized compounds showed anticonvulsant activity ranging from 50-90% (seizures protection). Compound 18 (5-(2'-phenothiazinylmethylene-5'-aminomethylene-1',3',4'-thiadiazol-2'- yl)-2-thiobarbituric acid) showed maximum activity being more potent than the reference drug phenytoin sodium (CAS 630-93-3).