Background: Early-onset dementia (EOD) is a rare condition, with an often atypical clinical presentation, and it may therefore be challenging to diagnose. Specialized memory clinics vary in the type of patients seen, diagnostic procedures applied, and the pharmacological treatment given. The aim of this study was to investigate quality-of-care indicators in subjects with EOD from 3 tertiary memory clinics in 3 European countries. Methods: We included 1325 newly diagnosed EOD patients, ages 65 years or younger, between January 1, 2007 and December 31, 2013, from the Danish Dementia Registry (Rigshospitalet, Copenhagen), the Swedish Dementia Registry ("SveDem", Karolinska University Hospital, Stockholm), and the Amsterdam Dementia Cohort (VU University Medical Center). Results: The frequency of EOD among all dementia patients was significantly lower in Copenhagen (410, 20%) and Stockholm (284, 21%) compared with Amsterdam (631, 48%). Not all quality indicator targets were met, such as the time to diagnosis, the mini-mental state examination score available, and the prescription of cholinesterase inhibitors. Cerebrospinal fluid sampling, registered in 2 sites, was performed in over 80% of the subjects. Conclusions: In tertiary referral centers in Copenhagen, Stockholm, and Amsterdam, quality indicators were not always met for patients with EOD. Results partly reflect differences in referral pattern, the application of diagnostic criteria, and local best practices. Standardized international procedures for patients with EOD may reduce this variability.