For a year now, Archimedes has sought to assist practising clinicians to give the best care to patients and families; paediatricians need to integrate the highest quality scientific evidence with clinical expertise and the opinions of the family 1 by providing "evidence based" answers to common questions which are not at the forefront of research, but are at the core of practice. In doing this, we are adapting a format which has been successfully developed by Kevin Mackway-Jones and the group at the Emergency Medicine Journal-"BestBets".A word of warning. The topic summaries are not systematic reviews, though they are as exhaustive as a practising clinician can produce. They make no attempt to statistically aggregate the data, nor search the grey, unpublished literature. What Archimedes offers are practical, best evidence based answers to practical, clinical questions.The format of Archimedes may be familiar. A description of the clinical setting is followed by a structured clinical question. (These aid in focusing the mind, assisting searching, 2 and gaining answers.3 ) A brief report of the search used follows-this has been performed in a hierarchical way, to search for the best quality evidence to answer the question. 4 A table provides a summary of the evidence and key points of the critical appraisal. For further information on critical appraisal, and the measures of effect (such as number needed to treat, NNT) books by Sackett 5 and Moyer 6 may help. To pull the information together, a commentary is provided. But to make it all much more accessible, a box provides the clinical bottom lines.The electronic edition of this journal contains extra information on each of the published Archimedes topics. The papers summarised in tables are linked, by an interactive table, to more detailed appraisals of the studies. Updates to previously published topics will hopefully be available soon from the same site, published as "rapid responses" to the original article.