To ensure that sedative agents in the intensive care unit are used for maximum benefit, a guideline that promotes the accurate and continuous assessment of patients' needs is indicated. This observational 24-month prospective study investigated the effect of introducing a sedation management guideline into a 10-bedded multidisciplinary intensive care unit on length of stay, severity of illness, mortality and the number of bed days provided. Costs for all sedative drugs were calculated as cost per bed day. Intensive care unit mortality remained constant before and after guideline introduction. The length of stay of non-cardiac surgery patients was mean (SD) 4.6 (4.4) and 5.1 (4.3) days, respectively (p = 0.2). Monthly sedative cost before guideline introduction was pound 6285 compared to pound 3629 afterwards (p<or =0.0001), representing a real saving of pound 63 759 in sedative costs over the 2 years following introduction of the guideline. Guideline-directed management for sedation significantly reduces the cost of sedative drugs per bed day without any negative effect on length of ICU stay and outcome.