A 9-year-old white boy presented with unruly hair since birth. Although his hair appeared to have normal growth without excessive loss or increased brittleness, it did not maintain its shape after styling. His older sister had experienced similar hair problems during childhood (Figure 1) but the condition had disappeared spontaneously with puberty. The hair of the other immediate family members was normal. On examination we observed the patient's entire scalp was covered with yellowish, dry, frizzy hair that projected outward and resisted any attempt to flatten it (Figure 2and Figure 3). The results of the rest of the clinical examination were unremarkable. On dermoscopy and electron microscopy (×10 and ×600 original magnification, respectively), a longitudinal grooving and a triangular shaft were found in examined hairs (Figure 4and Figure 5).