To assess the use of sedatives, analgesics and neuromuscular blocking agents in patients requiring mechanical ventilation in Danish ICUs, questionnaires were mailed to all Departments of Anaesthesiology in Denmark. Forty-nine out of 53 hospitals responded (92.5%). All ICUs surveyed used both sedatives and analgesics for patients undergoing mechanical ventilation. Opioids, benzodiazepines and propofol were employed most commonly, in particular by continuous infusion. Neuromuscular blocking agents were used at 65% of the ICUs surveyed, but only rarely. Ninety-eight percent of the ICUs reported side effects, but for less than 20% of the patients, secondary to the sedative treatment. Most frequent side effects were delayed emergence and gastrointestinal disorders.