Our objective was to develop a validated questionnaire that can measure the extent to which dimensions of caring affect the health of carers of patients with motor neuron disease. An initial 190-item questionnaire was developed from in-depth interviews, focus groups and two pilot studies with carers. Factor analysis was applied to the data obtained from a large survey in the UK that identified the underlying dimensions of caring. The newly formed scales were tested for reliability using Cronbach's alpha, and for construct validity. The SF36-v2 was the benchmark instrument on which correlations were made to ascertain the relationship with carers' health. A 34-item instrument was developed which has demonstrated promising evidence of internal reliability and validity for six scales: emotional well-being, physical well-being, self care, disturbed sleep, carers' support needs and statutory services. High correlations were found with the Mental Component Score summary scale of the SF-36v2 (0.40-0.66). The development and testing of the MNDCQ indicates that as the carers' score on the MNDCQ increases, suggesting a higher level of burden, they are more likely to report poor health. Further longitudinal studies are needed to further test the instruments' ability to detect change over time.