BACKGROUND: In Sub-Saharan Africa over one million newborns die annually. We developed a sustainable and scalable home-based counselling intervention for delivery by community volunteers in rural southern Tanzania to improve newborn care practices and survival. Here we report the effect on newborn care practices one year after full implementation. METHODS: All 132 wards in the 6-district study area were randomised to intervention or comparison groups. Starting in 2010, in intervention areas trained volunteers made home visits during pregnancy and after childbirth to promote recommended newborn care practices including hygiene, breastfeeding and identification and extra care for low birth weight babies. In 2011, in a representative sample of 5,240 households, we asked women who had given birth in the previous year both about counselling visits and their childbirth and newborn care practices. RESULTS: Four of 14 newborn care practices were more commonly reported in intervention than comparison areas: delaying the baby's first bath by at least six hours (81% versus 68%, OR 2.0 (95% CI 1.2-3.4)), exclusive breastfeeding in the three days after birth (83% versus 71%, OR 1.9 (95% CI 1.3-2.9)), putting nothing on the cord (87% versus 70%, OR 2.8 (95% CI 1.7-4.6)), and, for home births, tying the cord with a clean thread (69% versus 39%, OR 3.4 (95% CI 1.5-7.5)). For other behaviours there was little evidence of differences in reported practices between intervention and comparison areas including childbirth in a health facility or with a skilled attendant, thermal care practices, breastfeeding within an hour of birth and, for home births, the birth attendant having clean hands, cutting the cord with a clean blade and birth preparedness activities. CONCLUSIONS: A home-based counselling strategy using volunteers and designed for scale-up can improve newborn care behaviours in rural communities of southern Tanzania. Further research is needed to evaluate if, and at what cost, these gains will lead to improved newborn survival. TRIAL REGISTRATION: Trial Registration Number NCT01022788 (http://www.clinicaltrials.gov, 2009).