Marijuana and its cannabinoid constituents have profound effects on anterior pituitary hormone secretion. Exposure to delta 9-tetrahydrocannabinol inhibits gonadotropin, prolactin, growth hormone, and thyroid-stimulating hormone release and stimulates the release of corticotropin. Consequently, cannabinoid exposure could have profound effects on the function of the reproductive system, lactation, metabolism, and on the endocrine stress axis. The acute effects of cannabinoids on the endocrine system are consistent with its actions on brain neurotransmitter systems involved in the regulation of neuropeptides that modulate anterior pituitary hormone secretion. Although cannabinoid receptors appear to play a major role in the ability of cannabinoids to influence hormone release, much remains to be learned concerning their function in the neuroendocrine regulation of hormone secretion.