We discuss in this review the role of the neuregulin (NRG1) gene in schizophrenia. NRG1 contributes to the genetics of schizophrenia in both Icelandic and Scottish schizophrenia patients. NRG1 participates in glutamatergic signaling by regulating the N-methyl-D-aspartate (NMDA) receptor through the interaction of the NRG1 protein and its receptors. NRG1 plays a central role in neural development and is most likely involved in regulating synaptic plasticity, or how the brain responds or adapts to the environment. The discovery that defects in NRG1 signaling may be involved in some cases of schizophrenia, not only implicates NRG1, but suggests that its biological pathway, active both at developing and mature synapses, is worth inspecting further in a search for other schizophrenia genes possibly in epistasis with NRG1.