Background. Although poor language test performance has been documented in schizophrenia, its relationship to formal thought disorder remains unclear.

Method. Forty schizophrenic patients were administered eight language tests and, under blind conditions, rated for formal thought disorder. Measures of general intellectual function were also obtained.

Results. Performance on all language tests was significantly correlated with the general intellectual measures. Three language test scores also showed significant correlations with formal thought disorder scores. Multiple regression and analysis of intellectually preserved patients suggested particular associations of formal thought disorder with semantic comprehension and picture description.

Conclusions. General intellectual impairment is an important determinant of poor language test performance in schizophrenia, but presence of formal thought disorder may also contribute. A higher-order semantic deficit may be particularly relevant to both linguistic impairment and formal thought disorder.