Background: Recent advances in understanding the neurobiology underlying schizophrenia have underscored a pivotal role for a specific receptor for the neurotransmitter glutamate, the NMDA receptor, whose function may be impaired in the disorder. Enhancing transmission at the NMDA receptor may therefore provide a novel mechanism for treating schizophrenia. Over the past decade clinical trials that included supplementation with different compounds enhancing transmission at the NMDA receptor have provided positive results, particularly with D-serine. However, none of these trials focused specifically on young patients with recent onset schizophrenia. In addition, the optimal D-serine dose was not determined, although a preliminary report suggested that higher doses than those used in most studies may provide additional benefit, without significant safety concerns or side effects. Also, the pro-cognitive effects of D-serine were not systematically analyzed, although preliminary data supports a potential role for D-serine in ameliorating the cognitive deficits found in schizophrenia.