Abstract
The results of several experiments in which homovanillic acid (HVA) concentrations were measured, mainly in the cerebrospinal fluid, of schizophrenics are examined using Fisher's combination procedure. It is found that the data does not support the claim that the level of this dopamine catabolite is raised whereas some evidence strongly supports the claim that it is actually lowered. This finding is discussed in relation to the hypothesis of dopaminergic neuronal hyperactivity in schizophrenia.