Premenstrual symptoms are a common health condition in women that can impair their daily activities and overall quality of life. Although the severity of symptoms has been reported to be highly correlated with levels of perceived stress, how and to what extent these two are linked remains unclear. The objectives of this study were to identify the relationship between perceived stress and premenstrual symptoms, as well as to examine the impact of acculturative stress on this relationship among Korean international students. These students provide an excellent exemplar to study this phenomenon as they are the group with high stress levels due to additive acculturative stress while having common risk factors for premenstrual symptoms. The study used a 10-week longitudinal causal-comparative web-based study design. A convenience sampling method was used to recruit 98 Korean international students from the United States and 89 Korean domestic students from South Korea (comparison group). Weekly web-based surveys were administered for 10 weeks to capture the women’s levels of perceived stress, acculturative stress, and premenstrual symptoms for two consecutive menstrual cycles. The data were analyzed through descriptive analyses, linear multivariable mixed-model regressions, hierarchical multiple regressions, and path analyses, using SPSS 22.0 and Mplus 7.3. The levels of perceived stress and menstrual symptomatology were significantly higher during the premenstrual phase in Korean domestic students, while in Korean international students, levels of perceived stress did not differ by menstrual phases. Levels of perceived stress and menstrual symptomatology were significantly higher in Korean international students than in Korean domestic students throughout the menstrual cycle. Levels of perceived stress and acculturative stress were the strongest influencing factors for premenstrual symptoms in Korean international students. While perceived stress was a significant influencing factor for Korean domestic students, it was not the strongest factor. Psychological distress was a partial mediator between perceived stress and premenstrual symptoms in Korean international students, whereas perceived social support was a moderator between the relationship in Korean domestic students only. The findings of this study not only supported a significant relationship between perceived stress and premenstrual symptoms, but also the impact of acculturative stress on the relationship
