Seven 1-(naphth-1-ylacetyl)-4-substituted thiosemicarbazides were synthesized and cyclized to the corresponding 2-(naphth-1-ylmethyl)-5-arylamino-1,3,4-oxadiazoles. All compounds, with the exception of two slbstituted oxadiazoles, possessed low anti-inflammatory activity. The protection afforded by these compounds against carrageen-in-induced edema ranged from 3 to 43% where cyclization, in general, decreased anti-inflammatory activity. All compounds (1 mM), possessed antiproteolytic activity where in vitro protection of trypsin-induced hydrolysis of bovine serum albumin, in most cases was greater with oxadiazoles.