Estratetraenol, also known as estra-1,3,5(10),16-tetraen-3-ol, is an endogenous steroid found in women that has been described as having pheromone-like activities in primates, including humans. Estratetraenol is synthesized from androstadienone by aromatase likely in the ovaries, and is related to the estrogen sex hormones, yet has no known estrogenic effects. It was first identified from the urine of pregnant women.