Eighty consecutive Chinese patients diagnosed with Alzheimer disease were assessed for darkening of grey hair. Of the 62 eligible patients (mean age = 79.3 ± 7.9 years; male: female = 1:1.48), 24/62 (38.7%, 95%CI: 26.6 – 51.9) reported hair darkening after prolonged usage of cholinesterase inhibitor for at least 6 months. Of the 24 patients with hair darkening, 17 (70.9%) experienced hair darkening in the occipital region, 3 (12.5%) in the parietal region, 2 (8.3%) patients in the frontal region and 2 (8.3%) patients experienced hair darkening in multiple regions. Analysis of melanin concentration showed no significant difference between darkened hair of patients after prolonged drug use and the dark hair of controls (P = 0.381).