[3H]Flunitrazepam, [3H]PK 11195, [3H]quinuclidinyl benzilate (QNB) and monoamine oxidase (MAO) A and B activity were measured in male rats 1, 3 and 7 days following laparotomy. The surgery resulted in the up-regulation of central benzodiazepine (BZ) receptors in cerebral cortex and of peripheral BZ binding sites in brain and kidney on the first and third days after operation. This increase was followed by a decrease to normal range 7 days after the surgical procedure. [3H]QNB binding to muscarinic receptors in the cerebral cortex as well as MAO A and B activity in rat cerebral cortex and kidney were not affected by the surgical manipulation. The modulatory effect of surgery on BZ receptors corresponds to stages of the healing process in surgical wounds.