A 25-year-old woman transferred to pain clinic complaining of severe throbbing eye ball pain, eyelid edema and severe tearing in her left eye under the diagnosis of herpes zoster ophthalmicus that was developed 3months ago. In addtion to conventional medication, she had been taken stellate ganglion block, supraorbital and supratrochlear nerve block to contol of pain, but the response was poor. So we tried to administer ketamine subcutaneously, because not only ketamine, NMDA receptor antagonist, played a significant role to reduce neuropathic pain and pain caused by nerve injury, but also she wanted to work in her office during the treatment. We used subcutaneous ketamine 3 mg/hr (0.06 mg/kg/hr) in patient with postherpetic neuralgia of the ophthalmic nerve, and accomplished almost complete pain relief without any sign of side effect.