The aim of this study was to provide an evaluation of the overall effectiveness of using a number of clinical pathways in treating common acute paediatric conditions in an emergency department. This was a before and after study conducted on the effectiveness of three clinical pathways (gastroenteritis, asthma, and croup) in the emergency department of the Children's Hospital at Westmead, conducted over two separate yearly periods January to December 1996 and January to December 1999 representing before and after the introduction of clinical pathways in the emergency department. The main outcomes of the effectiveness of the pathways, namely admission to an in-patient bed, length of hospital stay and re-presentation after discharge from the ED were compared. Other outcomes of interest such as parental satisfaction and patient waiting times were also presented. Any deviation from a key clinical pathway process was reported. A total of 2854 children were managed by a clinical pathway compared to 2680 children managed before clinical pathways were introduced. The admission rate was reduced by threefold (9.1% compared to 23.6%) with a twofold reduction in length of hospital stay (32.7 h compared to 17.5 h). In 3.6% of children using a clinical pathway an unscheduled medical visit or re-presentation to the emergency department occurred after discharge, compared to 4.9% before the use of clinical pathways. No adverse events were reported in these children. In 76 cases deviation from a clinical pathway process was reported. High parental satisfaction was reported for clinical pathways throughout the study. Clinical pathways in this emergency department allowed rapid stabilisation of children, reducing admission rate, with a shortened length of hospital stay and few patients re-presenting after discharge and were well accepted by parents.