&NA;A number of studies using the repeat expansion detection (RED) technique have suggested an association between unknown large CAG/CTG repeats and schizophrenia. The polymorphic CAG/CTG repeat lociCTG18.1andERDA1have been reported to account for a high proportion (∼ 90%) of the large repeats detected by RED and may therefore be responsible for the cited association. The recently described locusTGC13‐7acontains a highly polymorphic CTA/TAG and CAG/CTG composite repeat, and is thus another authentic candidate. In the present investigation, each locus was analysed for association with schizophrenia in a sample of 206 patients and 219 group‐matched controls. No evidence for association ofCTG18.1, ERDA1and/orTGC13‐7awith schizophrenia was found. The combined data accounted for only 54% of the CAG/CTG arrays of > 40 repeats found in our previous RED analysis.