The overall aim of this dissertation was to examine the role of physical activity as a management and rehabilitation strategy for persons with MS. The research undertaken compared differences in fatigue, depression and quality of life measures in persons with MS who did and did not regularly participate in physical activity, assessed modifiable determinants of physical activity behaviour, as well as compared adaptations to two different exercise training modalities. To complete this research, three separate studies were conducted. The purpose of study one was to compare fatigue, depression and quality of life scores in persons with MS who did and did not regularly participate in physical activity. This was a cross-sectional questionnaire study of one-hundred and twenty-one patients with multiple sclerosis (MS). Study participants were 25-65 years old and lived in Queensland, Australia. Physical activity level, fatigue, depression and quality of life were assessed using the International Physical Activity Questionnaire, Health Status Questionnaire Short Form-36, Beck Depression Inventory and Modified Fatigue Impact Scale. Results indicated that fifty-two participants completed at least two, 30 minute exercise sessions per week (exercising group) and sixty-nine participants did not participate in regular physical activity (non-exercising group). Individuals in the exercising group reported favourable fatigue, depression and quality of life scores when compared to participants in the non-exercising group. We also found significantly weak correlations between both leisure-time and overall reported physical activity levels and some subscales of the quality of life and fatigue impact questionnaires. The findings of study one suggest that favourable fatigue, depression and quality of life scores are reported by persons with MS who regularly participate in physical activity, when compared to persons with MS who do not.