The synthesis and evaluation of a series of 3,5-disubstituted isoxazoles as antipicornavirus agents have led to the discovery of several compounds effective in vitro against rhinovirus type 2 and poliovirus type 2. Compound 32 was found more effective than 4',6-dichloroflavan against both viruses and was evaluated orally in mice infected intracerebrally with polio-2. At 31 mg/kg bid, compound 32 showed a 53% survival rate as compared to 22% for the nonmedicated animals.