Abstract: CHEN Zhuo*, LI Zhong-ming, FAN Wei-xin. *Department of Dermatology, Changhai Hospital, Shanghai 200433, China Corresponding author: FAN Wei-xin, Email：fanweixin@medmail.com.cn 【Abstract】 Objective To observe the morphological changes of hairs in two patients with loose anagen hair syndrome. Methods Light microscopy, scanning electron microscopy and transmission electron microscopy were used to observe the morphology of hair shaft and follicles from two patients, including a 3-year-old girl child and her mother, with loose anagen hair syndrome. Results Light microscopy revealed that hair bulb was deformed, hair shaft was distorted, damaged, and even disrupted, and hairs tapered in diameter at their distal end. Scanning electron microscopy showed deformed or distorted hair shaft and wave-like edge of hair cuticles. Trans- mission electron microscopy revealed that pathological changes were mainly localized in the inner root sheath with vacuolization in both inner and outer root sheath cells. Intercellular adhesion was weak with a decrease or disappearance of desmosomes. Conclusion The pathological changes of hairs are mainly localized in the inner root sheath in patients with loose anagen hair syndrome.