Dear Editor, TikTok, a video-focused social networking service with over 1 billion active monthly users, has been used to disseminate dermatologic information. 1 Previous studies have found discrepancies in the quality of videos based on the credentials of the content creator using the DISCERN instrument, a 16-item validated questionnaire that measures quality of consumer health information based on criteria including relevance, references, and treatment risks and benefits on a scale from 1 (poor) to 5 (excellent). [2][3][4] The primary aim of this study was to summarize diagnoses, content type, content creators and DISCERN scores of TikTok's most viewed alopecia-related videos.We conducted a cross-sectional, descriptive study to analyse the characteristics and reliability of the most viewed TikTok videos on alopecia areata, traction alopecia, trichotillomania, female and male pattern hair loss, alopecia universalis, telogen effluvium and frontal fibrosing alopecia. We conducted our search on 17 February 2022 and included the 25 most popular videos for each diagnosis, yielding 200 videos. Non-English videos, duplicates and advertisements were excluded, yielding 183 videos. We categorized the diagnosis, content type and content creator of all 183 videos (Table 1). Of videos categorized as 'educational', we further assessed their reliability and DISCERN scores (Table 2). Videos were deemed 'reliable' if they did not contain any information that conflicted with evidence-based guidelines. Two independent raters (B.N. and A.G.P.) assessed DISCERN scores. Identities of content creators were confirmed via biographic information on TikTok or other linked social media platforms; board-certified dermatologists were confirmed through the AAD. Interrater reliability was assessed using Cohen κ. Statistical analysis was performed using two-tailed t-tests, and p < 0.05 was considered statistically significant.Patients produced 64.5% (118/183) of videos, while boardcertified dermatologists produced 9.8% (18/183; Table 1). About 54.6% (100/183) of videos were categorized as primarily depicting 'personal experiences', followed by 32.8% (60/183) that were considered primarily 'educational'. Of these 'educational' videos, 70.0% (42/60) discussed treatments, 58.3% (35/60) aetiology, 15.0% (9/60) diagnosis and 8.3% (5/60) nutrition (Table 2). All videos posted by physicians (26/26) were considered 'reliable', compared with 56% (19/34) of videos posted by non-physicians. Board-certified dermatologists