Introduction Obsessional neurosis is considered to be resistant to behaviour therapy; the literature is reviewed by Marks et al. (1969). Wolpe and Lazarus (1966) described a ‘thought-stopping’ technique for this condition, but subsequent workers have largely ignored this method. In the case to be described, it was used experimentally with apparent success, and in view of the therapeutic nihilism felt about obsessional neurosis it was thought worthwhile to report this long-standing and previously resistant case.