OBJECTIVE To summarise the effects of anthelmintic drug treatment on growth and cognitive performance in children.   
 DATA SOURCES Electronic databases: Cochrane Infectious Diseases Group controlled trial register, Cochrane controlled trials register, Embase, and Medline. Citations of all identified trials. Contact with the World Health Organization and field researchers.    REVIEW METHODS Systematic review of randomised controlled trials in children aged 1-16 that compared anthelmintic treatment with placebo or no treatment. Assessment of validity and data abstraction conducted independently by two reviewers.   
 MAIN OUTCOME MEASURES Growth and cognitive performance.   
 RESULTS Thirty randomised controlled trials in more than 15 000 children were identified. Effects on mean weight were unremarkable, and heterogeneity was evident in the results. There were some positive effects on mean weight change in the trials reporting this outcome: after a single dose (any anthelmintic) the pooled estimates were 0.24 kg (95% confidence interval 0.15 kg to 0. 32 kg; fixed effects model assumed) and 0.38 kg (0.01 kg to 0.77 kg; random effects model assumed). Results from trials of multiple doses showed mean weight change in up to one year of follow up of 0.10 kg (0.04 kg to 0.17 kg; fixed effects) or 0.15 kg (0.00 to 0.30; random effects). At more than one year of follow up, mean weight change was 0.12 kg (-0.02 kg to 0.26 kg; fixed effects) and 0.43 (-0.61 to 1. 47; random effects). Results from studies of cognitive performance were inconclusive.   
 CONCLUSIONS There is some limited evidence that routine treatment of children in areas where helminths are common has effects on weight gain, but this is not consistent between trials. There is insufficient evidence as to whether this intervention improves cognitive performance.
True