Multiple sclerosis (MS) is a long-lasting neurological disease with onset in young adult age. Patients with MS are less active than healthy people, and their sedentary lifestyle might lead to secondary diseases or worsening of symptoms, disability and quality of life. In the study, we evaluated the attitude of physical activity (PA) of a group of MS patients and the differences in practice PA prior to and following the diagnosis. A randomly recruited group of patients with MS fulfilled a questionnaire about their attitudes towards PA before the onset and after the diagnosis of the disease. Clinical and demographic data were recorded. Out of 118 patients, 37% practiced PA only prior to the diagnosis, 9% only after and 52% during both periods. After the diagnosis, 64% of participants noted some negative differences in PA, in particular less physical resistance and worsening of symptoms, and 38% stopped PA. However, patients referred benefits from PA after diagnosis. Individual exercises rather than group activities were preferred after diagnosis. Only 26% of patients knew that adapted PA existed and the differences between adapted PA and classic physiotherapy. A reduction in the practice of PA in patients following the diagnosis of MS were observed, in particular for disease-related reasons. Nevertheless, active patients referred benefits from PA. It is important to know the point of view of patients towards developing individualized training programs. In this way, it could be possible to attain greater benefits from PA and reduce the negative effects.