16,16-dimethyl PGA2 is a metabolism resistant analog of PGA2 with a prolonged in vivo half-life. It inhibits the proliferation of Sendai virus in cultured African green monkey kidney cells by >90% at a concentration of 4 µg/ml. Daily infusion of 10 µg of 16,16-dimethyl PGA2 methyl ester into mice infected with influenza A virus increased survival by 40%. Similar treatment of mice inoculated with erythroleukemia cells delayed tumor growth and increased survival time.