Background: The pathogenesis of the post cardiopulmonary bypass (CPB) organ dysfunction syndrome is complex, with inflammation being an important component. The purpose of this prospective, randomized and controlled study was to evaluate the effect of a single dose of pentoxifylline (PTX) prior to CPB on high dependency unit time. Materials and methods: We studied 39 patients undergoing aorto-coronary bypass surgery with CPB. Patients received either 5 mg kg−1 PTX after induction of anaesthesia or saline as placebo. Haemodynamics, parameters of pulmonary function and plasma levels of tumour necrosis factor α (TNFα) and C-reactive protein (CRP) were measured after the induction of anaesthesia (pre-CPB) and after weaning from CPB (post-CPB), 1 h after the admission to the intensive care unit (ICU) and on the morning of the first postoperative day (1 POD), respectively. In addition, ventilation time and the high dependency unit time, i.e. the time till transferral to a peripheral ward, were documented. Results: Patients in the PTX group had lower TNFα values (6.3 ng ml−1 (4/8.2) vs 9.1 ng ml−1 (6.5/13.7)) (median (25%/75%), p = 0.021), lower systolic (28 ± 7 mmHg vs 35 ± 9 mmHg, mean ± SD, p = 0.011) and mean pulmonary artery pressures (21 ± 5 vs 26 ± 6 mmHg, p = 0.017) after admission to the ICU than control patients. Haemodynamics and pulmonary function parameters did not differ. There was a trend towards earlier weaning from the respirator in the PTX group (10.0 ± 3.5 h) (min/max: 4/16; confidence interval (ConF): 1.8 h) than the control group (12.3 ± 4.2 h) (min/max: 5–24; ConI: 2.4 h) (p = 0.077). Patients treated with PTX could be transferred to a peripheral ward about 24 h earlier than control patients (95 ± 35 h, min/max: 32/190 h; ConI: 17 h; 119 ± 29 h, min/max: 66/165 h; ConI: 16 h) respectively; p = 0.037). Conclusion(s): A single dose of PTX prior to CPB was able to reduce plasma levels of TNFα. In this descriptive study, there was a trend towards reduced duration of ventilation and the high dependency unit time, i.e. the time till transferral to a peripheral ward was shortened.