Objectives Previous studies revealed increases in the prevalence of chronic diseases in older people in most countries. This study investigated if a changed inclination to report diseases underlies these increases, by comparing the agreement between self-reports and general practitioner (GP) records of chronic diseases between 1992-1993 and 2008-2009. Study Design and Settings Cross-sectional analyses were performed on data from two waves of the Longitudinal Aging Study Amsterdam. Data from older adults aged 60-85 years came from 1992-1993 (N = 1,896) and from the same age group in 2008-2009 (N = 1,086). We compared respondent (R) and GP records of lung disease, cardiac disease, peripheral arterial disease, stroke, diabetes, arthritis, and cancer. Multilevel regression models were applied to examine (change in) predictors of over-reporting (R+, GP-) and under-reporting (R-, GP+). Results Over-reporting of chronic diseases became significantly more common over time, whereas under-reporting became less common. Agreement and change in agreement differed across the specific diseases. Under-reporting was associated with male gender; over-reporting with female gender, worse self-rated health, and worse physical functioning. Older adults were less accurate in their self-reports than younger adults. Conclusion Trends in self-reported chronic diseases may be influenced by changes in reporting behavior, and future studies should take this possibility into account. © 2014 The Authors. Published by Elsevier Inc. All rights reserved.