During the second half of the 1970s, the practice of the closed shop became widespread in some parts of the British public sector, but was resisted in others. This paper examines the issue in relation to the National Health Service, where trade unionists made frequent demands for the closed shop and where many managers were apparently not unwilling to concede it. Yet very few closed shops actually resulted. The paper examines the origin and patterns of these demands, health authority policies towards them, and their outcomes in terms both of the operation of the closed shops which were agreed, and the reasons for failure to agree. The conclusion is that although NHS industrial relations had apparently matured very rapidly between 1973 and 1977, the trade unions were neither strong enough nor united enough to enforce the closed shop; nor were industrial relations so far developed as to make the practice a natural next step.