Premenstrual syndrome (PMS) is a common but complex condition defined as a combination of emotional, psychological, and physical symptoms that occur during the luteal phase of the menstrual cycle, usually between 2 and 14 days before the onset of menstruation, and that diminish with menstruation. Epidemiological studies have reported that 80-90% of women experience premenstrual syndrome symptoms, with approximately 20-40% reported to affect daily functioning and relationships. Symptoms associated with PMS include irritability, mood swings, anxiety, depression, bloating, breast tenderness, and headaches. Pharmacological treatments such as selective serotonin reuptake inhibitors (SSRIs) and non-pharmacological methods such as dietary changes, exercise, and cognitive behavioral therapy are used in the management of PMS symptoms. Complementary herbal therapies are gaining increasing interest among individuals who want to avoid the side effects of traditional pharmacological agents. Various agents such as Vitex agnus-castus (chaste tree), Hypericum perforatum (St John's wort), evening primrose oil, and conventional herbal formulations have been studied in the literature. Vitex agnus-castus was found to be effective in relieving PMS symptoms by regulating hormonal balance. The antidepressant effects of yellow cantharone have been evaluated, but findings on its efficacy are inconsistent. Evening primrose oil shows particularly favorable effects on cyclic mastalgia. Lavender tea is known to reduce depression, anxiety, and mood swings. There are no clinical studies evaluating the effect of lavender tea on menstrual bleeding. A randomized controlled trial has shown that abdominal massage with lavender oil reduces the severity of menstrual pain. In this context, it may be a potential complementary herbal treatment to relieve PMS symptoms. Therefore, women with PMS will be divided into two groups. The intervention group will use 2 grams of lavender tea 2 times a day, morning and evening, for 9 days during 2 menstrual cycles (5 days before and 4 days after the estimated onset of menstruation). The control group will create a waiting list. The study data will be provided by 'Personal Information Form', 'Premenstrual Syndrome Scale', 'Depression Anxiety Stress-21 Scale', 'Premenstrual Syndrome Specific Quality of Life Scale', Visual Analogue Scale (VAS), and pad follow-up to monitor bleeding. SPSS 25.0 software will be used to analyze the data obtained from the study. Although the effects of lavender tea on PMS are promising, more clinical studies are needed to confirm its effectiveness. With this study, the need for clinical studies on the effectiveness of lavender tea will be met and a natural and complementary treatment method that can alleviate PMS symptoms will be tested.