PURPOSE: This qualitative study explored the perceptions of adults with multiple sclerosis about the positive and negative effects of a progressive resistance strengthening programme; and identified factors that might facilitate or create barriers to participation. METHODS: Seven women and two men (mean age 45.6 years, SD 10.7) with multiple sclerosis participated in a 10-week gymnasium based progressive resistance strengthening programme held twice a week. Participants were interviewed at the end of the programme. The recorded interviews were transcribed and then independently coded by three researchers. From these codes, the main themes emerged. RESULTS: Reports about the programme were very positive with physical, psychological and social benefits noted. Most participants said that they had less fatigue as a result of the programme. Few negative outcomes were reported and these were minor such as aches and pains. Key extrinsic factors for programme completion were the leaders' encouragement and knowledge of exercise; and the group aspect of the programme. Key intrinsic factors were enjoyment, determination, seeing the signs of progress, and a previously held positive attitude about the benefits of exercise. CONCLUSIONS: The results of this study suggest that progressive resistance strength training is a feasible fitness option for some people with multiple sclerosis. Factors perceived to be important for programme completion suggest that choosing encouraging leaders with knowledge of exercise, and exercising in a group may contribute to programme success.