It is desirable to reduce the number of treatments required to induce superovulation in cows. In this study we examined whether dissolving FSH in polyvinylpyrrolidone(PVP) would reduce the rate of absorption of FSH and allow it to be administered in a single dose for superovulation. In Experiment 1, 10 cows each received a single dose of FSH which contains 0.6% luteinizing hormone (FSH-R; 30 mg i.m.) dissolved in 30% PVP (10 ml) or in saline. In Experiment 2, a single injection of 30 mg FSH-R dissolved in 30% PVP was given to 25 cows, and 32 cows were injected twice daily in declining doses to receive a total of 28 mg FSH-R dissolved in saline. Prostaglandin F2alpha was given to all the cows 48 h after the first FSH treatment. Embryos were collected on Day 7 or 8 post insemination. In Experiment 1, the effect of FSH dissolved in PVP was compared with that dissolved in saline (number of recovered ova and embryos; 9.4+/-4.1 vs. 0). In Experiment 2, the rate of transferable embryos by single injection of FSH-R in PVP were significantly higher (P<0.05) than that of treatment of multiple injection groups. Progesterone concentration measured in serum collected 4 times from estrus (Day-0) to the day of embryo collection, indicated similar patterns in the 2 treatment groups. These findings suggest that PVP is a suitable solvent for prolonging the absorption of FSH given in a single injection thus providing a more practical approach of FSH administration.