Objectives:  To evaluate the concurrent and construct validity and the interrater reliability of the Face, Legs, Activity, Cry and Consolability (FLACC) scale during procedural pain in children aged 5–16 years. Background:  Self-reporting of pain is considered to be the primary source of information on pain intensity for older children but a validated observational tool will provide augment information to self-reports during painful procedures. Methods:  Eighty children scheduled for peripheral venous cannulation or percutaneous puncture of a venous port were included. In 40 cases two nurses simultaneously and independently assessed pain by using the FLACC scale and in 40 cases one of these nurses assessed the child. All children scored the intensity of pain by using the Coloured Analogue Scale (CAS) and distress by the Facial Affective Scale (FAS). Results:  Concurrent validity was supported by the correlation between FLACC scores and the children’s self-reported CAS scores during the procedure (r = 0.59, P < 0.05). A weaker correlation was found between the FLACC scores and children’s self-reported FAS (r = 0.35, P < 0.05). Construct validity was demonstrated by the increase in median FLACC score to 1 during the procedure compared with 0 before and after the procedure (P < 0.001). Interrater reliability during the procedure was supported by adequate kappa statistics for all items and for the total FLACC scores (κ = 0.85, P < 0.001). Conclusions:  The findings of this study support the use of FLACC as a valid and reliable tool for assessing procedural pain in children aged 5–16 years.