An investigation of hybrids of 2,5‐dimethyl‐1,3,4‐oxadiazole (I) and α,α,α,α',α',α'‐hexachloro‐p‐xylene (Hetol®) (II) as potential antimalarial agents led to the synthesis of representative 2‐phenyI‐5‐(trichloromethyl)‐1,3,4‐oxadiazoles (VIa‐f, VIII‐X) and related trichloromethyl 1,2,4‐oxadiazole, 1,3,4‐oxadiazoles, and 1,3,4‐thiadiazole (VII, XIII‐XV). Treatment of the appropriately substituted benzoic: acid hydrazides (IVa‐f) with trichloroacetic anhydride afforded the intermediate 1‐benzoyl‐2‐(triehloroacetyl)hydrazines (Va‐f) which were cyclized to the desired 5‐(chlorophenyl, tolyl, or α,α,α‐trifluorotolyl)‐2‐(trichloromethyl)‐1,3,4‐oxadiazoles (VIa‐f) (44–66%) in situ utilizing phosphorous oxychloride. Chlorination of the 5‐tolyl‐2‐(trichloromethyl)‐1,3,4‐oxadiazoles (VId‐f) afforded 2‐(trichloromethyl)‐5‐(α,α,α‐trichloro‐m‐ and p‐tolyl)‐1,3,4‐oxadiazole (VIII and IX) and 2‐(α,α,α,α',α',α'‐hexachloro‐3,5‐xylyl)‐5‐(trichloromethyl)‐1,3,4‐oxadiazole (X) in 23–56% yield. Each of the 2‐phenyl‐5‐(trichloromethyl)‐1,3,4‐oxadiazoles (VIa‐f, VIII‐X) was active against Plasmodium berghei in mice when administered in single 160 or 640 mg./kg. subcutaneous doses or given orally by drug‐diet for 6 days at doses of 29–336 mg./kg./day. The 2‐(trichloromethyl)‐5‐(α,α,α‐trichlorotolyl)‐1,3,4‐oxadiazoles (VIII‐X) were the most active compounds prepared and exhibited activity against P. berghei comparable with Hetol®. Structure‐activity relationships are discussed.