In the late 1990s, three prominent figures of 20th-century medicine—Paul Beeson, Howard Burchell, and Shimon Glick—exchanged private letters on the ethics of experimentation in the years following World War II. What began as a brief published back-and-forth blossomed into a long correspondence filled with humor and wisdom even in the face of continued disagreement. The history of postwar investigation unfolds memorably in their letters, starting with the whistleblowing of Beecher and Pappworth and moving into the 21st century. The heart of the discussion focuses on the ethics of consent and legitimate risk in clinical investigation, and on the prevalence of violations of patients' rights. Glick openly discusses his views about the widespread practice of their subjection to experiments without benefit or unrelated to their conditions. In opposition, Burchell claims that accusations of ethical misconduct during this period were exaggerated, and that most of these studies would pass review boards today. Just when things seem to reach an immutable impasse, Beeson weighs in with keen insight and personal experience. The debate provides not only an intimate perspective on some of the most influential physician investigators of the last half-century, but also a context for productively approaching ethical questions of today.