Reaction time and idiosyncrasy of word associations were examined in 30 schizophrenic patients, 2 h after administering a single dose of chlorpromazine, perphenazine or placebo. These patients were in the acute phase of their illness following 72 h cessation of oral neuroleptic treatment administered for 1-2 weeks. There was a statistically significant reduction in reaction times after administering perphenazine as compared to the placebo. Chlorpromazine showed some reduction in reaction times that was not statistically significant. Further study is needed to examine the relationship between such changes and other parameters, such as the patients' symptomatology and their social competence. Since many schizophrenic patients exhibit low or partial compliance, including patterns of intermittent taking of medication with a few days cessation, studies using such a model of a single dose of neuroleptic following several days withdrawal, may have clinical relevance. Another finding was a correlation between reaction time and the number of uncommon word associations produced. This correlation was beyond drug effect. Further study is needed to find out if such a correlation characterizes schizophrenic patients only.