Our aim was to test the findings of a study which claimed that, if the syntactic structure of schizophrenic speech were subjected to a detailed linguistic analysis, clear differences would be demonstrated between schizophrenic, manic and control populations. It was confirmed that schizophrenics do have less syntactically complex speech which contains more errors. Using linguistic variables in a discriminant function analysis, it was possible to predict diagnoses correctly in 79% of cases.