We measured the noradrenaline (NA), serotonin (5-HT) and dopamine (DA) contents of 47 normally maturated and 16 cystically degenerated follicular fluid samples obtained from patients involved in the in vitro fertilization and gamete transfer program. The patients were given human menopausal gonadotropin (HMG), as a superovulation treatment, and 7,500 IU human chorionic gonadotropin (HCG) to induce ovulation 34-36 h prior to the follicular puncture done by laparoscope. The NA content of the normally developed follicles was 11.4 + 8.4 micrograms/100 ml on average. For cystically degenerated follicles, the following data were obtained: 1.1 + 0.7 micrograms/100 ml (p less than 0.001). 5-HT and DA contents in the preovulatory follicles are 14.3 +/- 8.9 and 19.3 +/- 8.2 micrograms/100 ml, respectively; at the same time, 5-HT and DA contents in the cystically degenerated follicles were 12.2 +/- 6.2 and 12.7 +/- 6.8 micrograms/100 ml, respectively. They suggest that the higher amount of NA in the follicular fluid might play an important role in the mechanism of ovulation, the regulation of postovulatory tubal motility and the release of progesterone from granulosa cells.