Objective: 4-methoxy-N, N-dimethyl-6-(phenylthio) pyrimidin-2-amine, 4-(benzo [d]thiazol-2-ylthio)-6-methoxy-N,N-dimethylpyrimidin-2-amine, 4-(4-(1,2,3-selenadiazol-4-yl)phenoxy)-6-methoxy-N,N-dimethylpyrimidin-2-amine and 4-(4-(1,2,3-thiadiazol-4-yl)phenoxy)-6-methoxy-N,N-dimethylpyrimidin-2-amine have been synthesized. Method: The prepared compounds were synthesized by nucleophilic displacement of chloride substituted in pyrimidine heterocyclic ring. Results: The synthesized compounds were being identified by different methods included TLC technique, IR, 1H-NMR and 13C-NMR spectrophotometers. All compounds confirmed by elemental analysis. The biological activity of these new compounds investigated against some fungi like Aspergillus terreus and Aspergillus niger, the results was Aspergillus terreus more effected by antifungal compare with Aspergillus niger, the effect ration 0.98, 1.32 with 200µM respectively and the compound number (2) has more effect than other compounds. Conclusion: It is concluded that synthesized dimethylpyrimidin-derivatives are biologically active and developed into useful Antifungal agents. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.