Many published clinical trials are poorly designed, suggesting that the protocol was incomplete, disorganised or contained errors. This fact, doctors' limited statistical skills and the shortage of medical statisticians, prompted the development of a knowledge-based aid, Design-a-Trial, for authoring clinical trial protocols. Design-a-Trial interviews a physician, prompts and guides them through suitable design options, comments on the statistical rigour and feasibility of their proposed design, and generates a 6-page draft protocol document. This paper reviews the progress of the Design-a-Trial project by describing a working prototype and its recent and planned development.