The major association thalamic nuclei, the mediodorsal nucleus (MD) and the medial pulvinar nucleus (PUM) are regarded as important parts of the circuits among association cortical regions. Association cortical regions of the frontal, parietal and temporal lobes have been repeatedly implicated in the neuropathology of schizophrenia. Thus, the aim of the present postmortem study was to investigate the volumes of association thalamic nuclei in this disease. The volumes of the whole thalamus (THAL), MD and PUM were measured in each hemisphere of brains of 12 patients with schizophrenia and 13 age-matched and gender-matched normal control subjects without neuropsychiatric disorders. Patients with schizophrenia exhibited significant volume reductions in both the MD and the PUM, the reductions being more pronounced in the PUM. The volume of the PUM in the left (-19.7%, P=0.02) and right (-22.1%, P=0.01) hemispheres was significantly reduced in the schizophrenia group. The volume of the MD was reduced in both hemispheres in the schizophrenia group. However, the volume reduction was only significant in the left hemisphere (-9.3%, P=0.03). Patients with schizophrenia also exhibited a decreased volume of the THAL in the left (-16.4%, P=0.003) and right (-15.2%, P=0.006) hemispheres. There were no significant correlations between thalamic volumes and duration of illness or age of the patients. In conclusion, the present data indicate volume reductions of association thalamic nuclei in schizophrenia. These anatomical findings are consistent with the view that schizophrenia may be associated with disturbances of association cortical networks. However, the findings of a substantial volume reduction of the THAL suggest that the volumes of additional thalamic nuclei may be also reduced in schizophrenia.