Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease. The first line treatment of AD relies on the daily use of emollients to restore the skin barrier impairment associated with the disease. Vitreoscilla filiformis (V.f.) is a non photosynthetic bacterium and extracts of V.f. are endowed with properties which balance cutaneous immune-homeostasis. The aim of our study was to investigate the efficacy and safety of a 5% V.f. extract-containing ointment on mild to moderate AD in a randomised, double-blind, vehicle-controlled trial. Thirteen patients applied the treatment and the vehicle on symmetrical AD lesions (left versus right side of the body) twice daily for 4 weeks. The assessment of AD severity was done at each visit (Day 0, Day 14 and Day 28) using the modified eczema area and severity index (mEASI). Treatment with the ointment containing 5% V.f. extract significantly improved the AD skin symptoms. Beneficial effects were observed after two weeks of treatment and increased thereafter. These results suggest that V.f. extract could be favourably added to AD skin care emollients formulated for AD.