We will collect breath samples of a representative group of MS patients of all types and of age-matched controls. Our GC-MS chemical analysis will address: (1) the dependence of the MS breath biomarker levels on the type/stage of the MS disease; and (2) the effect of environmental factors such as age, diet, lifestyle (especially smoking and drinking habits) on the chemical composition of the breath. Based on the results of the GC-MS chemical analysis, we will improve and optimize our array of nanosensors setup so as to achieve: (1) maximum sensitivity to the MS biomarkers and their stage dependent concentration profiles; (2) minimum sensitivity to non-MS related changes of the chemical composition of the breath, and (3) minimum sensitivity to the major ingredients of the breath, such as water vapor. We will attempt to define MS sub-categories, supported by the information from the clinical/imaging reports, which might be relevant for clinical management, by more sophisticated statistical treatment of the collected data. Towards the end of this proof-of-concept study we will compare the performance of our electronic nose setup to the conventional MS diagnostic tools. The comparison will be done in terms of true positive, true negative, false positive, false negative, sensitivity and specificity.