The diagnosis of systemic sclerosis (SSc) is not always simple, especially in the early stage of the disease. This is due to considerable changes in the extensiveness of skin changes, different degrees of internal organs involvement, and variable dynamics of the disease. It is often difficult to foresee the speed of disease development. The division of patients into subgroups with various courses of the disease and various internal organs involvement coupled with distinguishing clinical symptoms, makes it easier to predict the prognosis in SSc. There have been numerous attemps to establish clear classification criteria necessary for diagnosis of a disease accompanied with internal organs involvement. It is essential in the diagnosis to determine if the disease is in active changes phase or in the advanced irreversible phase. This diagnosis influences the type of therapy chosen for a patient. There are also attemps to establish an activity index of the disease and the scale of different organs impairment. In this study we have tried to present some methods of the disease activity assessment and some ideas how to check these methods usefulness for choosing the right therapy. Intensive immunosupressive treatment can be accepted in the period of increased disease activity, but not in the period of irreversible SSc process.