We examined the effect of systemic androgen levels upon the rate at which lumbosacral motoneurons are labeled with cholera toxin-conjugated horseradish peroxidase (CT-HRP) injected into target muscles. CT-HRP first reaches the spinal nucleus of the bulbocavernosus between 8 and 10 h after injection into the bulbocavernosus muscle of adult male rats, but the number of motoneurons filled with CT-HRP does not differ between androgen-treated and control castrates at any of the time points examined. Thus, contrary to current speculation, we found no evidence that androgen can affect retrograde transport of CT-HRP by rat motoneurons.