Estradiol USP was extemporaneously compounded for intravenous administration. Eight postmenopausal women were randomized to receive one of four estradiol dosages. Serum estradiol concentrations were determined at frequent intervals after single bolus dosing. The concentration-time profile was stripped and fit, and pharmacokinetic values were generated. Approximate dosage proportionality was seen with area under the curve, the terminal halflife was 27.45 ± 5.65 minutes, and volume of distribution was very low (0.082 ± 0.015 L/kg). Estradiol was well tolerated by all study participants.