Six Silastic levonorgestrel-releasing capsules, Norplant, were introduced subcutaneously into the ventral aspect of the left forearm or upper arm of thirteen patients immediately after first trimester pregnancy termination. Blood samples were taken twice a week over two months after abortion and from one subject over one month after removal of Norplant capsules. Plasma concentrations of levonorgestrel were measured by radioimmunoassay and the effects of treatment on pituitary and ovarian function were determined by assaying plasma concentrations of LH, FSH, estradiol and progesterone. If removal of Norplant capsules took place because of planning pregnancy, the subjects were asked to inform us if they had become pregnant. During the first month after abortion the mean levonorgestrel concentration (489 pg/ml) was statistically significantly higher than during the second month (237 pg/ml). The mean estradiol values fell to prefollicular levels within four days, remaining a little suppressed. The mean progesterone concentrations were below 2 ng/ml three days after abortion. Three subjects had a transient increase in plasma progesterone concentrations nine days after abortion. Thereafter no ovulatory progesterone concentrations were seen. The LH concentrations ranged within normal values of the follicular phase and FSH values were just beneath the lower limit of follicular phase FSH values, apart from a few peaks, indicating mild suppression. After removal of Norplant capsules, progesterone concentrations increased to ovulatory levels fifteen days after removal. The Norplant capsules were removed from two subjects because of planning pregnancy and they delivered healthy babies 9.5 and 12.5 months after removal.