Levosimendan is an inotropic drug with organ-protective properties due to its activation of mitochondrial K(ATP) channels. This prospective, randomized, double-blind, placebo-controlled study investigated whether administration of levosimendan prior to cardiopulmonary bypass could reduce organ dysfunction and influence subsequent secondary endpoints. Patients with left ventricular ejection fraction <30% scheduled for elective coronary artery bypass surgery (with or without valve surgery) received either levosimendan (12.5 mg, 0.1 µg kg(-1) per min; n = 17) or placebo (n = 16) central venous infusion, immediately after anaesthesia induction, as add-on medication to a goal-orientated treatment algorithm. A total of 33 patients completed the study. There were no statistically significant differences in Sequential Organ Failure Assessment scores, survival, haemodynamic parameters, time to extubation, time in intensive care unit, need for haemodialysis or health-related quality-of-life at 6 months post operation. The levosimendan group compared with the placebo group had significantly lower use of epinephrine (35% versus 81%) and nitroglycerine (6% versus 44%) 24 h postoperation, and significantly less frequent serious adverse events (13% versus 47%). These preliminary results show that timely perioperative levosimendan treatment is feasible, has a favourable safety profile safe and may help to prevent low cardiac output syndrome. However, organ function was not preserved. Further studies, using larger sample sizes, are required.