The inhibitory effect of activated charcoal 50 g suspended in water on the absorption of digoxin, phenytoin and aspirin was studied in six healthy volunteers in a cross-over manner. The absorption of digoxin and phenytoin were almost completely prevented (about 98%) when activated charcoal was ingested immediately after the drug. The total absorption of aspirin was inhibited by 70%; with clear postponement of absorption and partial release of aspirin from the charcoal in the gut: The peak serum concentration of aspirin was reduced by 95% by charcoal. When activated charcoal was ingested 1 hour after the drugs the inhibition of absorption was considerably less. However, since the absorption of larger doses of the drugs is often slow, the administration of an adequate dose of activated charcoal will be of definite value in the treatment of acute intoxication, even if delayed for several hours.