Sulfotransferase 4A1 (SULT4A1) is a novel sulfotransferase expressed almost exclusively in the brain. The gene is located on chromosome 22q13.3, a region implicated in predisposition to schizophrenia. Recently, a variable microsatellite region located upstream of SULT4A1 was found to be associated with an increase in schizophrenia risk. We hypothesised that if functional dysregulation of SULT4A1 was involved in the aetiology of schizophrenia, then genetic variants in the coding sequence of SULT4A1 might be identified in cases compared with controls. To test this, we carried out a mutation analysis of the coding region (exons 2-7) in 71 Australian schizophrenia cases and 69 controls. We found no mutations, either synonymous or nonsynonymous, in either cohort. However, intronic variants (IVS5+12 C>T and IVS5+28 G>C) were identified, the frequency of which was not statistically different between cases and controls. The lack of polymorphisms in the coding region of the SULT4A1 gene is highly unusual and, along with its high conservation between species, suggests that SULT4A1 may have an important function in vivo. However, our findings do not support the hypothesis that germline mutations in the coding region of SULT4A1 contribute to susceptibility to schizophrenia.