The human uterus, including its blood vessels, contains hCG/human LH receptors. We now demonstrate that human fallopian tubes also contain a 4.4-kilobase hCG/LH receptor mRNA transcript and an 80-kilodalton immunoreactive protein that can bind [125I]hCG. Tubal mucosa contain more receptor transcripts, receptor protein, and [125I] hCG binding than the tubal smooth muscle or blood vessels. Human fallopian tubes also contain hCG protein and a 0.6-kilobase hCG alpha mRNA transcript. However, very little hCG is found in tubal cell layers other than mucosa. Ampullary segments contain more hCG/LH receptors and hCG than isthmus. Secretory phase tubes contain more than proliferative phase, postpartum, or postmenopause tubes. Incubation with highly purified hCG resulted in an increase in catalytically active 5-lipoxygenase, cyclooxygenase-1, and cyclooxygenase-2 enzymes in tubal tissues. In summary, human fallopian tubes, which have never previously been considered a direct target of hCG/LH action, express functional hCG/LH receptor gene as well as the gene of its ligand. These novel findings suggest numerous possibilities of both physiological and pathological importance in human fallopian tubes.