2, 7-Diethyl-5H-pyrazolo[1, 5-b][1, 2, 4]triazole derivatives were synthesized and evaluated for activity as angiotensin II receptor antagonists. Replacement of the C-6 hydrogen with C-linked oxygen functional groups led to derivatives with increased in vitro activities. Among these compounds, 2, 7-diethyl-5-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-5H-pyrazolo[1, 5-b][1, 2, 4]triazole-6-carboxylic acid (2d) showed potent, insurmountable antagonism, but had poor oral potency against angiotensin II-induced pressor response in rats. In order to improve the oral activity, the carboxylic acid function of 2d was converted into a double ester. This modification afforded (±)-1-[(ethoxycarbonyl)oxy]ethyl 2, 7-diethyl-5-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-5H-pyrazolo[1, 5-b][1, 2, 4]triazole-6-carboxylate (2f), which was orally active in rats, and produced a dose-dependent decrease in blood pressure when administered orally to conscious furosemide-treated dogs, with ca. 3-fold increased potency in comparison with the parent C-6 hydrogen compound.