This study explores the severity of depression and anxiety experienced by patients suffering from motor neurone disease and seeks to link this to illness progression, recent life events and personality factors. The 18 patients who participated in the study were assessed for the presence of psychiatric symptoms using the Beck Depressive Inventory and the Hospital Anxiety and Depression Scale. The severity of the illness and the life events during the course of the illness were measured using the Norris scale and the Holmes and Rahe Social Readjustment Rating Scale. A personality assessment was made using the Eysenck Personality Questionnaire (EPQ). Only four out of these 18 patients (23%) in the study suffered depression and of these three (17%) were mild and one (6%) was of moderate severity. A further six patients (33%) were rated as borderline depression. Only two patients suffered from an anxiety state and both had concurrent mild depression. No correlations of depression were found with the life events or illness progression. Only the L sub-scale of the EPQ (15.6+/-4.9) exceeds values expected for the general population. Despite the severity and frequency of life events during the course of the illness, most patients do not develop a depressive illness. The reason for this unexpected result is unclear. Depression is believed to result from underactivity of the serotonergic neurotransmitter system. However, in MND this system is relatively unaffected in contrast to dementia and other neurodegenerative disorders. The patients' high L scores suggest that many may cope with their illness by widespread use of denial as a psychological defence.