Although the autopsy still is a valuable tool in health statistics, health care quality control, medical education, and biomedical research, autopsy rates have been declining worldwide. The aim of this study was to examine trends of overall, clinical and forensic autopsy rates among adults in the Netherlands over the last four decades, and trends per sex, age (groups), and hospital type. We performed a retrospective study covering 35 years of Dutch national death counts (1977–2011), the number of in-hospital deceased patients, the number of deaths due to external causes, and the proportion of autopsies performed in these populations. The effects of sex, age and hospital category were analysed by linear and logistic regression and differences were evaluated by chi-square tests. Overall autopsy rates declined by 0.3% per calendar year, clinical autopsy rates by 0.7% per calendar year (from 31.4% to 7.7%), and forensic autopsy rates did not decline. Per calendar year the fraction of in-hospital deceased patients decreased by 0.2%. Autopsy rates were highest among men and younger patients; clinical autopsy rates were highest for patients dying in academic hospitals. In the Netherlands clinical autopsy rates have rapidly declined while at the same time the fraction of in-hospital deaths decreased, both contributing to the overall reduced absolute number of autopsies performed. It is important to improve awareness among both clinicians and general practitioners of the significance of the clinical autopsy.