Deficits in slow-wave sleep (SWS), or delta sleep, are frequently seen in schizophrenia, but their relationship with schizophrenic symptomatology remains unclear. We examined the association between visually scored and automated measures of SWS and positive and negative symptoms in a series of unmedicated patients with schizophrenia and related psychotic disorders. Total and average automated delta wave counts were significantly inversely associated with negative symptoms overall, and the psychomotor poverty syndrome in particular. Total delta counts were also inversely related to the disorganization syndrome. No relation was seen between reality distortion or the Brief Psychiatric Rating Scale (BPRS) positive symptoms and SWS. These findings support the view that SWS deficits may be related to negative symptoms of schizophrenia and may perhaps be mediated by impaired functioning of frontothalamic neural circuits.