The present study examined whether long-term supplementation with once- and twice-weekly multiple micronutrients (MMN-1 and MMN-2) can improve Hb and micronutrient status more than twice-weekly Fe–folic acid (IFA-2) supplementation in non-anaemic adolescent girls in Bangladesh. An equal number of 324 rural schoolgirls aged 11–17 years were given MMN-1 or MMN-2 or IFA-2 supplements for 52 weeks in a randomised, double-blind trial. Blood samples were collected at baseline, and at 26 and 52 weeks of supplementation. The girls receiving IFA-2 supplements were more likely to be anaemic than the girls receiving MMN-2 supplements for 26 weeks (OR 5·1, 95 % CI 1·3, 19·5; P = 0·018). All three supplements reduced Fe deficiency effectively. Both the MMN-1 and MMN-2 groups showed significantly greater improvements in vitamins A, B2 and C status than the girls in the IFA-2 group, as might be expected. Receiving a MMN-1 supplement was found to be less effective than MMN-2 supplement in improving Fe, vitamins A, B2 and folic acid status. Receiving micronutrient supplements beyond 26 weeks showed little additional benefit in improving micronutrient status. In conclusion, given twice-weekly for 26 weeks, MMN supplements can improve micronutrient status effectively with no significant increase in Hb concentration compared with IFA supplements in non-anaemic Bangladeshi adolescent girls. However, it significantly reduces the risk of anaemia. Before any recommendations can be made, further research, including into cost-effectiveness, is needed to see whether MMN supplementation has any additional longer-term health benefits over that of IFA supplementation in this population.