The purpose of the present study was to investigate stress, anabolic and catabolic hormonal levels and their association with interleukin 6 (IL-6) cytokine in patients undergoing lumbar spine fusion (LSF) surgery. Blood samples were collected preoperatively, and at 1, 3, 42 and 90 days postoperatively (POD) from 49 LSF patients with a mean (SD) age of 62 (11) years. Serum concentrations of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH), insulin-like growth factor 1 (IGF-1), testosterone, sex hormone-binding globulin (SHBG) and IL-6 were analyzed. In women, cortisol concentration rose above baseline values despite a fall in ACTH levels. GH showed a decrease on PODs 1 and 3 whereas IGF-1 levels remained stable. In males, SHBG increased, and both testosterone and free testosterone showed a decrease during PODs 1-3. The other hormone concentrations had returned to normal by PODs 42 or 90, except for IGF-1, which remained above the baseline value on PODs 42 and 90. IL-6 correlated significantly with cortisol (p <0.001) level on POD 1. The results suggest that hypercortisolism after operative stress is caused by cytokine-induced non-ACTH-driven cortisol production or reduced cortisol breakdown suppressing the production of ACTH via feedback inhibition. Furthermore, GH levels decrease rapidly.