There is a widespread belief among clinicians that trifluoperazine (Tr) is more effective than chlorpromazine (Ch) in activating retarded schizophrenic patients. We examined the effect of these two drugs on the motor activity of three groups of inactive patients: A, very inactive; B, moderately inactive and C, mildly inactive. All these patients were under 60, with at least 10 years duration of illness. We excluded those with subnormality or physical illness and those who had a leucotomy. They were all sufficiently inactive to fall below the mid-point on the Venables scale (Venables, 1957), so that an increase in activity constituted an improvement. The same supervisors and raters were used throughout and attempts were made to maintain the work environment as constant as possible. The raters did not have access to their earlier scores.