1. The effects of an orally administered single dose of placebo, acetylsalicyclic acid (ASA) and (d,1)-6-chloro-a-methyl carbazole-2-acetic acid (carprofen) have been evaluated on an experimental pain model by electrical stimulation of dental pulp in man. 2. ASA and carprofen showed a significant analgesic action, while placebo was ineffective. 3. Analgesic activity of ASA and carprofen was similar. The two drugs were ineffective in modifying the pain threshold; on the contrary, the tolerance to the strongest painful sensation was significantly increased.