Sedative effects of single and repeated doses of 50 mg and 150 mg tolperisone hydrochloride (Mydocalm), a centrally active muscle-relaxing agent, were evaluated in a placebo-controlled double-blind clinical trial. A total of 72 healthy young adults balanced by sex were randomized to receive 50 mg or 150 mg tolperisone hydrochloride or placebo t.i.d. for a period of 8 days. Control examinations were performed in the mornings of days 1 and 8 before intake of the morning dose and at 1.5, 4 and 6 hours postdose. The psychomotoric test battery used in this trial revealed no sedative effects of tolperisone hydrochloride in the given doses at any control examination. Subjective mood ratings quantified by the Welzel Colored Scales were not impaired either. The lack of differences in sedative potentials of tolperisone hydrochloride and placebo was confirmed by tests on differences and by tests on equivalence using 95% CI. The present study substantiates clinical experience and previous clinical trials demonstrating that tolperisone hydrochloride, though being a centrally active muscle relaxant, does not cause any sedation and does not impair reaction times.