Depression relapse rates are high, therefore, identifying factors related to mental health and treatment outcome is important. We examined differences between inpatients with a stress-related depression and healthy controls regarding narcissism, stress, resource alterations, exhaustion, and depression. Twenty-one healthy controls and 36 inpatients with a stress-related depressive disorder completed questionnaires assessing vulnerable and Journal of Psychiatry and Psychiatric Disorders grandiose narcissism (PNIvn, PNIgn), perceived stress (PSS), resource gain and actual or threatened resource loss during the past six months (COR-Egain, COR-Eloss, COR-Eloss?), vital exhaustion (MQ), and depression severity (BDI-II). Depression severity was additionally assessed using the HAMD17. Most data was assessed repeatedly, i.e. after treatment initiation, before treatment termination, and at six months follow-up. Inpatients revealed significantly higher levels of PSS, MQ, BDI-II, HAMD17, and PNIvn, while PNIgn reached a trend significance level. In healthy controls, PNIvn correlated positively with COR-Eloss. In inpatients, PNIvn was positively related to levels of PSS, COR-Eloss, COR-Eloss?, and BDI-II, while PNIgn was positively correlated with levels of PSS. Higher PNIvn at the beginning was further significantly associated with a stronger decrease in PSS until follow-up, and in BDI-II until the end or follow-up. These results underline the importance of personality factors in the treatment of stress-related depression.