A group of aryl-Z-alkoxy-5-benzylpyrimidines wherein Z is oxy, thio, imino, carbonyl, carbamoyl, sulfonyl, sulfinyl or sulfamoyl has been prepared from 2,4-diamino-5-benzylpyrimidine via alkylation with either an aryl-Z-alkyl halide or a substituted glycidyl ether. These compounds are potent dihydrofolate reductase (DHFR) inhibitors which are useful as antibacterial, anti-protozoal and antitumor agents.