This study aimed to determine the number and distribution of spermatozoa within the human Fallopian tubes around ovulation. Parous women, undergoing total abdominal hysterectomy for menorrhagia, were inseminated with either partner's semen (3/10) or donor semen (7/10). Approximately 18 h later both Fallopian tubes were ligatured into ampullary, isthmic and intramural regions. These were removed and assessed for sperm content by flushing, scanning electron microscopy (SEM) or homogenization. A median of 251 spermatozoa were recovered (range, 79-1386). The number of spermatozoa within each tube was not significantly different. The ovulatory ampulla contained a significantly (P < or = 0.01) larger percentage of spermatozoa than the non-ovulatory ampulla. The number of motile spermatozoa inseminated was not significantly correlated to the number of spermatozoa recovered, but a trend was identified. The time between the onset of the luteinizing hormone surge and hysterectomy was significantly correlated (P < or = 0.01) to the number of spermatozoa within the intramural regions, but not to the tubal sperm distribution. Spermatozoa were not observed, by SEM, bound to the tubal epithelium. These data suggest that, after artificial insemination at least, sperm access to the human Fallopian tube may be controlled, but that ovulation does not affect the redistribution of spermatozoa between tubal regions and that the isthmus does not appear to act specifically as a sperm reservoir.