This briefing paper provides an overview of known examples of unethical clinical trials. It was prepared by SOMO, in collaboration with Wemos, and is based on secondary sources. Although the focus is on developing countries, it also includes a few cases from the US and Europe. By providing such an overview, the paper aims to illustrate problems in the ethical conduct of clinical trials. It does not provide an analysis of clinical trials in general or of the scale of ethical violations. Indeed, the scale of the problem is unknown, because it cannot be estimated how many unethical clinical trials escape public attention and therefore remain unnoticed.