The effects of single oral doses of 5, 10, and 20 mg temazepam were evaluated with the adaptive tracking test, analysis of smooth-pursuit and saccadic eye movements, and visual analog lines in a placebo-controlled, double-blind, crossover experiment with 12 healthy volunteers. Pharmacodynamic testing was performed until 10 hours and pharmacokinetics were evaluated until 24 hours. Temazepam, 20 mg, caused effects in all tests, with peak effects occurring at 30 minutes. The 10 mg dose caused effects on saccadic eye movements and subjective scores of alertness, whereas 5 mg temazepam was detected only by analysis of saccadic eye movements. Linear relationships between plasma concentrations and effects were found in nine subjects for saccadic peak velocity and eight subjects for subjective scores of alertness. The results of this study demonstrate manifest differences in the sensitivities of performance tests and stress the importance of validation of methods when effects of drugs on human performance are studied.