People with multiple sclerosis (MS) tend to have lower participation in paid employment compared to those with other chronic diseases. In two large-sample, self-report surveys of MS patients performed 4 years apart, employment rates were measured both cross-sectionally and longitudinally. The reasons for employment loss and perceived risk of future employment loss were also assessed. A total of 1,135 patients responded to the first survey, 1,329 to the second, and 667 to both. Longitudinal loss of employment was 5.4% over the 4 years 2003-2007, a period of relative national economic prosperity. By 2007, 56% of MS patients had lost employment due to MS and 64% were not in the paid labour force. Regression analysis indicated that men were more likely than women to leave their employment because of their MS, and older people were more likely than younger ones to do so. Level of occupational skill using Australian Bureau of Statistics categorisation was not predictive of maintaining or losing employment. The main reasons reported by people with MS for their loss of employment involved the ineffective management of symptoms of MS in the workplace, rather than workplace-related factors including insufficient flexibility of employment conditions or being asked to leave or sacked. The most frequently listed symptoms relating to employment loss, and perceived risk of losing current employment, were fatigue, mobility-related symptoms, arm and hand difficulties, and cognitive deficits. These findings imply that many employees with MS are leaving their planning for effective symptom management, and for appropriate accommodations in the workplace, until such planning is too late to be effective. The potential advantages of early, supported disclosure of diagnosis to employers before MS symptoms become a problem are discussed.