A series of novel 4,5-dihydro-4-oxo-5,5-disubstituted-2-furancarboxylic acids was synthesized and shown to possess potent hypotriglyceridemic activity in normal rats. In contrast to clofibrate, none of the present compounds altered liver weight at any dose. Being more potent than nicotonic acid and clofibrate, 4,5-dihydro-5-methyl-4-oxo-5-phenyl-2-furancarboxylic acid (5b, AY-25,712) has been selected for clinical trials.