The authors evaluated the relationship between hormonal and cytokine responses after surgery. Patients who underwent thoracic oesophagectomy (O group;n=7), pulmonary lobectomy (P group;n=5), modified mastectomy (M group;n=5) and laparoscopic cholecystectomy (LC group;n=7), were randomly selected. Circulating neutrophil and lymphocyte numbers were assayed. Changes in the concentration of the hormones [adrenocorticotrophic hormone (ACTH), cortisol, and antidiuretic hormone (ADH)] and cytokines [tumour necrosis factor α (TNF-α), interleukin 1β (IL-1β), IL-6, and IL-10[ were analysed. In O and P groups, neutrophils wee still seen on post-operative day (POD) 3, while the leukocyte counts of M and LC groups returned to normal. The number of lymphocytes significantly decreased on POD1 and POD3 only after oesophagectomy. The pattern of hormonal levels was consistent in all groups. While TNF-α and IL-β were undetectable in the peripheral blood, the concentration of IL-6 and IL-10 increqased in O and P groups, but not in M and LC groups. The degree of lymphocytepenia and neutrophilia correlated well wth the extent of surgical trauma.