The effect of repeated dose oral activated charcoal on quinine elimination has been studied following a therapeutic (600 mg) dose of quinine bisulphate to seven normal volunteers. Activated charcoal lowered quinine half-life from 8.23 +/- 0.57 s.d. h to 4.55 +/- 0.15 s.d. h (P less than 0.001) and increased its oral clearance by 56%. Activated charcoal may have a role in the management of quinine poisoning.