AIMS AND OBJECTIVES: To evaluate the concurrent validity and reliability of the behavioural COMFORT and a modified version of the FLACC scale for assessment of pain and sedation in intubated and ventilated children and to evaluate the construct validity of the FLACC scale for assessment of pain. BACKGROUND: Few instruments are available for assessment of pain/sedation in paediatric intensive care. DESIGN: A prospective observational study was performed postoperatively in 40 children aged 0-10 years. METHODS: Two trained nurses observed the child simultaneously and assessing COMFORT behavioural (COMFORT-B) and FLACC scores. In comparison, two bedside nurses concurrently scored pain using an observational visual analogue scale (VAS(obs)) and sedation using the Nurse Interpretation of Sedation (NIS) score: oversedated, adequately or insufficient sedated. In 20 additional patients, one nurse assessed FLACC scores before and after analgesics. RESULTS: The majority of patients were 3), both COMFORT-B and FLACC scores were significantly different compared with VAS(obs)