A CAUSAL RELATIONSHIP between sex steroids and meningioma proliferation has long been suspected. We report a case of the clinical progression of a sphenoid wing meningioma after the placement of Norplant, a subcutaneous contraceptive implant containing levonorgestrel, a progesterone agonist. Although not proof of causation, this observation lends further credence to the importance of progesterone receptors in the growth and possible treatment of meningiomas.