This case demonstrates a clear on/off phenomenon of anorgasmia related to gabapentin, which may be dose related. The frequency of this adverse effect is unknown, although sexual side effects were reported as uncommon in clinical trials when epilepsy was treated. It is unknown if gabapentin might affect other areas of sexual functioning, although, in this man, it did not. The mechanism of action of gabapentin is unknown, and the effects on ejaculation or other aspects of sexual function are also unknown. As gabapentin becomes more commonly used in psychiatric practice, the frequency of this adverse effect may become more apparent.