Background. Pregnancy is one of the most sensitive periods in a woman's life, causing great changes and emotional instability. Pregnancy, apart from the pleasure of being a mother, is the most stressful period of the life of women. Objectives. This study aimed to investigate the relationship between mothers' personality types and their perceived stress. Material and methods. This cross-sectional descriptive-analytic study was conducted on 210 eligible mothers in three hospitals affiliated with the Shiraz University of Medical Sciences. Personality and Perceived Stress Questionnaires were completed by the mothers. Data analysis was performed with Pearson and Spearman statistical tests, using SPSS software (version 22). Results. The highest score of the personality type belonged to the conscientiousness, with an average score of 39.68 ± 6.09. The highest frequency was also related to conscientiousness personality type (48.1%). Mothers in the study had a moderate perceived stress level, with a mean score of 26.98. Using the Pearson correlation test, we found there was a significant positive relationship between the two variables of neuroticism and perceived stress (r = 0.149, p = 0.031). There was also a significant relationship between openness to experience and perceived stress (r = 0.265, p = 0.001). Conclusions. according to the results, personality types are related to the level of perceived stress in mothers, and maternal stress can be predicted through personality traits. Therefore, identifying the personality types, training of mothers and holding psychotherapy sessions can be very important.