Setting: Academic medical center. Results or Clinical Course: On examination, the patient had weakness of his right gluteus medius, tibialis anterior, tibialis posterior, peronei and extensor hallucis longus muscles. There was reduced sensation to pinprick over his dorsolateral right foot. Magnetic resonance imaging of his lumbar spine was unremarkable for neural compression. Electrodiagnostic studies revealed changes that localized either to the right sciatic nerve or sacral plexus. He was diagnosed with right lower limb weakness due to herpes zoster infection. Following physical therapy, he regained some functional strength of the right foot and was able to ambulate with an anklefoot-orthosis and cane. Discussion: Herpes zoster infection occurs due to reactivation of the varicella zoster virus. Over 90% of the reported cases are in immunocompetent individuals and the greatest risk factor is increased age. Zoster-associated limb weakness is an uncommon complication and has been reported in 3% of individuals with herpes zoster infections. The pathophysiology of zoster-associated limb weakness is hypothesized to be viral-mediated injury to the anterior horn cell or dysmyelination of the peripheral nerve. Conclusions: Zoster-associated limb weakness is a rare complication of herpes zoster infection, but should be included in the differential diagnosis of acute limb weakness.