We studied asymptomatic primary schoolchildren in northeastern Malaysia with light to moderate trichuriasis to determine the effect of albendazole treatment on growth rates and TNF-alpha levels. Thirty-seven schoolchildren aged 6-7 years with stool samples positive for Trichuris trichiura and negative for other geohelminths and protozoa were randomized to receive albendazole 400 mg or a placebo daily for 2 days. Anthropometric parameters at baseline, 3, 6 and 12 months were compared between the 2 groups. The placebo group had a significantly greater increase in height (p = 0.04) than the albendazole treatment group. There were no significant differences in urinary TNF-alpha levels (p = 0.8) between the 2 groups and no significant changes between baseline and 1 month post-treatment levels. Further studies are needed to determine the etiology of this apparent association between the albendazole treatment group and the delay in growth rate at 6 months post-treatment.