The goal of the study was to examine whether individuals with multiple sclerosis differ from healthy individuals in their assertiveness, self-esteem and perception of stress. Participants (N = 60) in the study were female. The first group (n = 30) consists of people with diagnosed MS, while the other group (n = 30) consists of participants from the general population. Participants in the group with diagnosed MS were recruited through social media groups which gather these people and they independently filled out the questionnaires which they accessed over the internet. Participants without diagnosed MS were also recruited through social media and they filled out the same questionnaires with the same instructions. The set of questionnaires consists of Rosenberg's Self-esteem Scale, Rosenberg, 1965, PSS Perceived Stress Scale, Cohen, 1983, and Assertiveness Scale (Mihaljević, 2006). In order to get information about the condition of the participants prior to MS diagnosis, or from an equivalent period of life in the general population, both groups filled out two versions of the questionnaire. One version of the questionnaire referred to the current situation, and the other version required the participant to give a retrospective response about the condition from the period before being diagnosed and the equivalent period for healthy participants, respectively. The results indicate a lower degree of assertiveness among participants in the group diagnosed with MS.