Schizophrenia is a complex, heterogeneous behavioural and cognitive syndrome whose origins appear to lie in genetic and/or environmental disruption of brain development. Dysfunction of dopaminergic neurotransmission appears to contribute to the genesis of psychotic symptoms but the evidence also points to a more widespread and variable involvement of brain areas and circuits. There is emerging evidence that disturbances of synaptic function might underlie abnormalities of neuronal connectivity possibly involving interneurons, but the precise nature, location and timing of these events is uncertain. Current treatment consists largely in the administration of antipsychotic drugs combined with psychological therapies, social support and rehabilitation, but there is a pressing need for more effective treatments and for services to be delivered more effectively. Progress in understanding the disorder has been great in recent years with advances in genomics, epidemiology and neuroscience, and the opportunities for further scientific advance are great: but so are the challenges.