Objective: To study multi-center variability of medial temporal lobe atrophy (MTA) in patients with Alzheimer’s disease (AD) recruited in a European observational study of AD. Methods: 117 mild to moderate AD patients from 5 European centers (Amsterdam, The Netherlands; Brescia and Genova, Italy; Mannheim, Germany; Pamplona, Spain) had magnetic resonance imaging scans performed as part of the routine diagnostic examination. MTA was assessed with the visual Scheltens scale. Results: AD patients from Brescia, Genova, Pamplona, and Mannheim had a mean 32% prevalence of no or borderline MTA vs. 62% of patients from Amsterdam (p = 0.002 for the difference between Amsterdam and all the other centers). The peculiar distribution of MTA in the Amsterdam patients may be attributable to younger age (70.7 ± 8.4 vs. 75.3 ± 6.8 years, p = 0.002), milder dementia severity (score 0.5 on the clinical dementia rating scale: 52 vs. 23%, p = 0.003), and less frequent depression (14 vs. 49%, p < 0.0005 in Amsterdam vs. all the other centers, respectively). Conclusion: Patients with probable AD recruited in different centers of Europe generally have similar MTA distribution, even if peculiar demographic and clinical findings might explain occasional differences. These results have implications for clinical trials in AD with biological markers as outcome measures.