The aim of this study was to empirically investigate the effect of death-awareness on state mindfulness and state integrative self-knowledge. For existentialists, confrontation with the fact of one’s personal death and tolerance of its inevitable anxiety is the most fundamental conflict of human beings. If such confrontation occurs, it leads to enhancement of one’s self-awareness. Empirical testing of this existential assumption in a sample of multiple sclerosis patients as well as a sample of non-patients was the target of the study. Being plagued by such a disabling chronic disease was considered to be a boundary situation in which people are prone to existential suffering and probably better candidates for existential interventions. In this pseudo-experimental study, 32 female patients with MS and 34 female non-patients were chosen by accessibility method of sampling and were assigned to four groups: patient experimental group, patient control group, non-patient experimental group, and non-patient control group. Then in the experimental groups, an intervention supposed to induce death-awareness in participants was held in contrast to control groups whose intervention was not related to death. State mindfulness and state integrative self-knowledge were measured before and after intervention by State Mindfulness Scale (Brown & Ryan) and State Integrative Self-knowledge Scale (Ghorbani) respectively. The results of multivariate analysis of co-variance (MANCOVA) showed no significant difference between the groups. These findings may challenge terror management theory (TMT). Explanatory hypotheses and their theoretical implications are discussed.