This study was carried out in a university hospital located in the southeastern region of Turkey to determine the relationship between the perceived stress with the religious attitude and behavior of the intensive care patient's relatives; 150 patient's relatives participated in this descriptive and relation-seeking study between the dates of January and April 2019. The Personal Data Form, Perceived Stress Scale, and Religious Attitude and Behavior Inventory that were designed by their own researchers as a result of the literature review were used in this study. As a result of this study, it was found that there was a statistically significant relationship between religious attitude and behavior and perceived stress levels of the patient's relatives with sociodemographic features such as age, gender, marital status, and educational level. It was determined that the participants mostly prefer to pray as a method for stress management (65.3%). In terms of educational level, it was identified that 42% of the participants are elementary school graduates; besides, the stress level of this group was significantly lower than the others, and their religious attitude and behaviors were higher (p = 0.004). In consideration of these results, in terms of holistic care, it is recommended that nurses should make arrangements toward their strategy for stress management considering the religious attitudes and behaviors of patients' relatives.