Background: Dry skin (xerosis cutis) is increasingly recognized as a relevant health problem in daily life and in health and nursing care. The use of bath additives such as oils is common to reduce dry skin, but empirical evidence supporting this practice is limited. Objectives: The aim of this study was to investigate the effectiveness of using a bath oil additive in improving skin barrier function and ameliorating dry skin in comparison to non-oil containing skin cleansers for bathing or showering. Design: Single centre randomized observer blind pragmatic parallel group trial. Settings: Outpatient/community care. Participants: Volunteers showing clinically mild to moderate dry skin recruited from the city of Berlin. Methods: Healthy children and adults were randomly assigned to use either a commercially available bath oil or to continue using their regular non-oil containing skin cleansers every other day over a study period of 28 days. Skin barrier parameters and the severity of dry skin were assessed at baseline and at two follow-up visits at the study centre. Transepidermal water loss was the primary outcome. Results: All sixty participants randomized completed the trial. Median age was 32.5 (IQR 83 to 69) years. At the end of study the mean transepidermal water loss in the intervention group was statistically significant lower compared to the control group (mean difference -1.9 (95% CI -3.1 to -0.8) g/m(2)/h). Stratum corneum hydration was statistically significantly higher in the intervention group at the end of the study. Skin surface pH and roughness were comparable in both groups and remained unchanged, while both groups showed a trend to improvement in dry skin symptoms Conclusions: This pragmatic trial provides empirical evidence that the regular use of the investigated bath oil is effective in improving the skin barrier function in children and adults with mild dry skin when used in routine skin care and supports its use as a basic element for the management of a broad spectrum of dry skin conditions. (C) 2016 Elsevier Ltd. All rights reserved.