Background: Correct hair wash frequency and the right product are essential for scalp and hair care. Women wearing hijab are becoming more common. However, no consensus has been published regarding the correct frequency of hair washing, especially for women wearing hijab. Research is needed to compare the influence of different hair wash frequencies on scalp health. The aim of this study is to assess the correlation between hair wash frequency with scalp transepidermal water loss (TEWL) and hydration in women wearing hijab. Methods: Sixty healthy women in reproductive age were allocated into 30 subjects in Group A (frequent hair wash, every 1–2 days) and 30 subjects in Group B (infrequent hair wash, every 3–5 days). Measurements of scalp skin TEWL and hydration were performed on baseline, day‑14, and day‑28. Results: The day‑28 median value of scalp skin TEWL was 20.87 g/m2/h in Group A and 17.67 g/m2/h in Group B (P < 0.01). The day‑28 median value of scalp skin hydration was 11.48 AU in Group A and 12.77 AU in Group B (P > 0.05). Conclusions: Frequent hair wash may significantly increase scalp TEWL score in women wearing hijab. However, there is no correlation between hair wash frequency and scalp hydration in women wearing hijab. © 2025 International Journal of Trichology.