BACKGROUND Infusion of hypertonic saline provides early haemodynamic benefits and may affect the immune system. It is unknown if infusion of hypertonic saline affects plasma cytokines and stress hormones after surgery. METHODS Sixty-two women undergoing abdominal hysterectomy were randomized in a double-blind study to infusion of NaCl 7.5% (HS), NaCl 0.9% (NS4), both 4 ml kg(-1), or NaCl 0.9% 32 ml kg(-1) (NS32) over 20 min. Blood was collected at baseline, 1, 4, and 24 h after surgery (n=34) for the determination of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12, IL-1ra, and tumour necrosis factor-alpha. Serum cortisol and vasopressin were measured at these time points and 48 h after operation. Epinephrine and norepinephrine (n=26) were quantified at baseline, after infusion, 25 min after incision, 1, and 4 h after surgery. Finally, C-reactive protein was measured at baseline, 24, and 48 h after surgery. RESULTS Surgery and anaesthesia induced well-reported changes in the concentrations of cytokines and hormones. The concentration of norepinephrine briefly increased after infusion of HS and NS32 but not NS4 (P<0.05). Epinephrine was increased 25 min after incision in Group NS32 compared with the other groups (P<0.05). No other differences were found between the groups. CONCLUSIONS Infusion of a clinically relevant dose of hypertonic saline before hysterectomy appears to have limited effect on the postoperative concentration of selected plasma cytokines and the hormonal stress-response.