The effects of practice on a range of performance measures often used in studies of psychoactive drugs have been assessed in 50 normal healthy adult volunteers, during 10 practice sessions over an 8-day period. There was no dramatic effect of practice on any of the parameters measured, only one of the mean values at the tenth session exceeded one standard deviation of the mean of the first session (manipulative motor task). Practice did not materially affect performance on elapsing time estimation, tapping rate, body sway measured by a ultrasonic method or rapid visual information processing task variables. There tended to be a non-significant, exponential learning curve for choice reaction response and movement times to visual stimuli, flash fusion threshold and the manipulative motor task, with a statistically significant practice effect on all 16 visual analogue scales used; a plateau was apparently achieved by the fifth practice session for all these parameters. There was a statistically significant straight-line improvement in digit span across the 10 sessions. It is concluded that for most simple measures of performance used in psychopharmacology including visual analogue scales, four pre-study training sessions are necessary, and that direct methods of recording body sway are preferred to indirect methods such as the balance platform.