The purpose of this study was to prospectively study the human pharmacokinetics of an ultrasound (US) contrast agent through its active ingredient, dodecafluoropentane (DDFP). Expired air and blood samples were collected from 24 volunteers after IV administration from 0.01 to 0.1 mL/kg. It was concluded that DDFP pharmacokinetics in blood has fast elimination. The drug is exhaled unmetabolized. Recovery in expired air was almost complete 2 h after administration.