This study aimed to examine health care professionals' knowledge of neuroleptic malignant syndrome (NMS). A meta-analysis of 16 pieces of international literature on the subject, published in the decade 1980-1990, identified five areas of knowledge which their authors felt were the most important aspects of the syndrome. These included: being able to define the condition; knowing what drugs were associated with the onset of NMS; being aware of the common manifestations of the disorder; having knowledge of other conditions which have similar symptoms to NMS, and how the syndrome is treated. A multiple-choice questionnaire was administered to a nonrandomized convenience sample of 40 pharmacists, doctors and nurses in the United Kingdom, and to 30 nurses in six other countries (India, Germany, Holland, Japan, USA and France). Two open-ended questions were also asked of the participants to ascertain their attitude to having knowledge of NMS. Analysis of the responses showed that the majority of health care professionals tested in this way did not know enough about NMS to aid early detection of the syndrome and to prevent loss of life.