A 31-year-old woman developed acute visual loss in her right eye immediately after a 5-day course of CC for primary infertility. Although she gradually recovered vision, she did not return to 20/20 acuity in that eye. As CC may cause vascular sludging, it is hypothesized that increased blood viscosity resulted in sufficiently reduced flow in a posterior ciliary artery to produce an anterior ischemic optic neuropathy. Patients experiencing visual symptoms while taking clomiphene should have their eyes examined promptly for evidence of visual changes or optic nerve injury.