| - Low nutritional value of complementary foods is associated with high incidence of childhood growth stunting in low-income countries. This study was done to test a hypothesis that dietary complementation with lipid-based nutrient supplements (LNS) promotes linear growth and reduces the incidence of severe stunting among at-risk infants. A total of 840 6-month-old healthy infants in rural Malawi were enrolled to a randomised assessor-blinded trial. The participants received 12-month supplementation with nothing, milk-LNS, soy-LNS, or corn-soy blend (CSB). Supplements provided micronutrients and approximately 280 kcal energy per day. Outcomes were incidence of severe and very severe stunting [length-for-age z-score, (LAZ) < -3.00 and <-3.50, respectively], and change in LAZ. The incidence of severe stunting was 11.8%, 8.2%, 9.1% and 15.5% (P = 0.098) and that of very severe stunting 7.4%, 2.9%, 8.0% and 6.4% (P = 0.138) in control, milk-LNS, soy-LNS and CSB groups, respectively. Between 9 and 12 months of age, the mean change in LAZ was -0.15, -0.02, -0.12 and -0.18 (P = 0.045) for control, milk-LNS, soy-LNS and CSB groups, respectively. There was no significant between-group difference in linear growth during other age-intervals. Although participants who received milk-LNS had the lowest incidence of severe and very severe stunting, the differences between the groups were smaller than expected. Thus, the results do not provide conclusive evidence on a causal association between the LNS supplementation and the lower incidence of stunting. Exploratory analyses suggest that provision of milk-LNS, but not soy-LNS promotes linear growth among at-risk infants mainly between 9 and 12 months of age.