In this systematic review effectiveness of analgesics for pain after tonsillectomy in children was evaluated and trial methodology of the included studies explored. Databases were searched for randomised, controlled studies on systemic paracetamol, NSAIDs and opioids. Eighty-four studies were evaluated for inclusion. Thirty-six studies were included and 48 excluded. Only in two studies investigated analgesics were given postoperatively for pain. All other studies investigated prophylactic administration of analgesics. Only five studies were truly placebo controlled. Trial methodology of the included studies varied greatly in respect to analgesics and doses used, duration of follow-up periods, methods of pain measurement, rescue analgesics and criteria for administrating rescue analgesia used. Sensitivity of studies was often unclear. Only 16 out of 36 studies were considered to be sensitive. Because of highly variable methodology and lack of sensitivity only limited conclusions on clinical efficacy of analgesics investigated can be drawn. No analgesic in single prophylactic dose provided analgesia for day of operation. Further studies are needed to find the optimal analgesic(s) for pain after tonsillectomy in children.