Preanaesthetic medication with clonidine. The purpose of this study was to evaluate oral clonidine in a dose of 0.3 mg as a routine premedicant. Sixty-nine normotensive female patients were studied in a randomized double-blind investigation in which clonidine was compared with an inert treatment. Clonidine produced a significant reduction in anxiety (P less than 0.05) and sedation and a reduction in the sleep dose of methohexitone (P less than 0.05). Tachycardia in response to intubation was attenuated by clonidine (P less than 0.05). However, the magnitude of the increase in arterial pressure after intubation was not affected. Intraoperative and postoperative hypotension were common after premedication with clonidine 0.3 mg and caution is urged in its use as a premedicant. 