Healthcare research is haunted by a history of unethical studies in which profound harm was caused to vulnerable individuals. Official systems for gaining ethical approval for research, designed to prevent a repetition of these shameful examples, can prove bureaucratic and inflexible in practice. The core ethical principles of respect for autonomy, prevention of harm, promotion of benefit, and justice (which form the basis of professional codes of research conduct) must be applied flexibly to take account of contextual, methodological, personal and practical considerations. Ensuring that the design and conduct of all research is ethically sound is the responsibility of all involved-including researchers, research institutions, ethics review committees and regulatory bodies.