There is a strong prima facie case linking the abuse of psychiatry with difficulties about the concept of mental illness. However, a survey of recent Soviet literature showed that the concept of disease employed in the former USSR (where abuse was for a time widespread) was similar to its counterparts in the UK and USA in being strongly scientific in nature. A number of factors--legal, bureaucratic and professional--are important in abuse becoming widespread. These, however, fail to explain why psychiatry, rather than physical medicine, should be vulnerable to abuse. It is here that the concept of disease could be important. A scientific model of disease suggests that a significant vulnerability factor is the relatively underdeveloped status of psychiatry as a science. This leaves room for poor standards of scientific work in clinical research and practice, factors which are recognised as important in the Soviet case. In addition to the scientific element, there is an evaluative element of meaning in the concept of disease. Hence a second vulnerability factor could be the evaluatively problematic nature of judgements of mental illness. It is concluded that a failure to recognise this factor greatly increases the vulnerability of psychiatry, not only to gross abuses, but also to inadvertent misuses of involuntary treatment in everyday practice. This conclusion, far from undermining the role of science in psychiatry, is a step towards clarifying its proper role.