Abstract The objective of this analysis is to report the effect of dupilumab treatment on skin barrier function and patient-reported outcomes (PROs) in adults and adolescents with moderate-to-severe atopic dermatitis (AD). BALISTAD (NCT04447417) was an open-label trial in which transepidermal water loss (TEWL) was assessed repeatedly before and after skin tape stripping (STS) samples were taken from lesional and nonlesional skin of 26 patients with AD treated with dupilumab, and from normal skin of 26 matched healthy volunteers aged 12–65 years over a period of 16 weeks. PROs assessed included Patient-Oriented Eczema Measure (POEM), Peak Pruritus Numerical Rating Scale (PP-NRS) and Dermatological Life Quality Index [DLQI; for patients > 17 years old; Children’s DLQI (CDLQI) for patients aged > 12 to < 17 years]. At baseline, the median TEWL after five STS was statistically significantly higher in the lesional and nonlesional skin of patients with AD compared with healthy skin (P < 0.001 and P < 0.01, respectively) and statistically significantly decreased following dupilumab initiation as early as week 2 (P < 0.001 and P < 0.05, respectively). After 16 weeks of dupilumab treatment, there was no statistically significant difference in adjusted mean TEWL in AD lesional and nonlesional skin compared with matched healthy skin (P = 0.225 and P = 0.163, respectively). Significant improvement from baseline [mean (SD) change from baseline] was seen as early as week 2 in mean POEM [−8.4 (5.1)], DLQI [−5.3 (4.7)], CDLQI [−6.2 (4.7)] and PP-NRS [−2.2 (1.8); P < 0.001 and P < 0.05)] for CDLQI. Improvement was sustained through to week 16 [mean (SD) change from baseline; P < 0.001] for POEM [−13.6 (8.5)], DLQI [−8.6 (7.4)] and PP-NRS [−4.2 (2.6)] and with a P-value of < 0.01 for CDLQI [−9.2 (5.0)]. Dupilumab treatment normalizes epidermal barrier function in lesional and nonlesional skin in patients with moderate-to-severe AD, as measured with TEWL, and improves PROs. Funding sources: research sponsored by Sanofi and Regeneron Pharmaceuticals Inc.