We report the first case of a massive accidental overdose of nevirapine in a 1-week newborn, due to confusion between nevirapine (Viramune) and nelfinavir (Viracept). The drug was eliminated spontaneously and quickly. We only observed mild neutropenia and hyperlactatemia, which regressed on its own without any clinical complication. Despite the good evolution of this massive overdose, physicians should be aware of confusion risks between some antiretroviral drugs.