Objectives: Amyotrophic lateral sclerosis (ALS) is a fatal disease with unique demands on patients and carers. Patients and methods: The total burden of care and burden components in 37 ALS carers were measured using validated questionnaires. Furthermore, influencing factors (functional impairment of the patient, additional carers, participation in support groups) were assessed. Results: The mean total burden of care for ALS was low compared with dementia, mixed neuropsychiatric and internal diseases, but was correlated with functional impairment (P = 0.003). The main burden components were 'personal and social restrictionsfland ’physical and emotional problems‘. Problem behaviour of the patients was low in general, but was higher in carers participating in support groups (P = 0.002). Carers supported by additional carers had higher strain. Conclusion: The low burden of ALS carers may be caused by the low incidence of problem behaviour in ALS patients. However, if problem behaviour exists, carers participate more often in support groups, indicating the need for assistance. The burden of care increases with the functional impairment. Support for the carers has to start sooner.