Background: Primary dysmenorrhea is a common gynecological condition that negatively affects women's daily activities, well-being, and quality of life. Exercise is known to reduce menstrual pain; however, the added contribution of pressure biofeedback during abdominal strengthening remains unclear. Objective: This study aimed to examine the effects of abdominal strengthening exercises performed with a Stabilizer Pressure Biofeedback Unit (PBU) on menstrual symptoms, pain intensity, and abdominal muscle strength in women with primary dysmenorrhea. Methods: This randomized, controlled, single-blind clinical trial included 58 women aged 18-25 years with regular menstrual cycles and a Visual Analog Scale (VAS) score of >= 4. Participants were randomly allocated to an intervention group (n = 27) or a control group (n = 31). Both groups completed an eight-week lumbopelvic and core strengthening exercise program, while the intervention group additionally performed PBU-assisted abdominal training during the same period. Assessments were conducted at baseline, week 4, and week 8. Outcome measures included abdominal muscle strength assessed with PBU, menstrual symptoms measured using the Menstrual Symptom Questionnaire (MSQ), and pain intensity evaluated by VAS. Results: Both groups demonstrated significant improvements in abdominal muscle strength and pain intensity over time (p < 0.05). However, no significant between-group differences were observed in muscle strength, VAS, or MSQ scores at any assessment point (p > 0.05). Conclusion: Lumbopelvic and abdominal strengthening exercises reduced menstrual pain and improved abdominal muscle strength in women with primary dysmenorrhea. Adding PBU-assisted training did not produce superior outcomes compared to conventional exercise alone. Future studies should explore longer interventions and combined approaches to address symptoms.