BACKGROUND: There is an increasing global burden of disease from injuries. Models of trauma care initially developed in high-income countries are also being adopted in low and middle-income countries (LMIC). Amongst these ambulance crews with Advanced Life Support (ALS) training are being promoted in LMIC as a strategy for improving outcomes for victims of trauma. However there is controversy as to the effectiveness of this health service intervention, and the evidence has yet to be rigorously appraised. OBJECTIVES: To quantify the effectiveness of ambulance crews with ALS training versus crews with any other level of training in reducing mortality and morbidity in trauma patients. SEARCH STRATEGY: We searched the Cochrane Controlled Trial Register (CCTR), the specialised register of the Cochrane Injuries Group, MEDLINE, EMBASE, CINAHL, PubMed and the National Research Register. We checked references of background papers and contacted authors to identify additional published or unpublished data. SELECTION CRITERIA: Randomised controlled trials, quasi-randomised controlled trials and controlled before-and-after studies comparing effectiveness of ambulance crews with ALS training versus crews with any other levels of training in reducing mortality and morbidity in trauma patients. Studies which compared crews staffed by physicians versus others were excluded. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied eligibility criteria to trial reports for inclusion and extracted data. MAIN RESULTS: We found one randomised controlled trial, which included 16 trauma cases. However, outcome data were added to the main non-randomised cohort in the analysis, and data on these 16 cases are not yet available. REVIEWER'S CONCLUSIONS: In the absence of evidence of the effectiveness of advanced life support, strong argument could be made that it should not be promoted outside the context of a properly concealed and otherwise rigorously conducted randomised controlled trial.