The article presents a series of three cases where bilateral anterior quadratus lumborum block (AQLB) with 20 mL of 0.375% ropivacaine on each side provided significant relief of menstrual pain in primary dysmenorrhea. Truncal fascial plane blocks have been shown to be effective in the treatment of chronic and refractory nonsurgical pain. AQLB provided immediate relief in the first month after the procedure. The effect clearly lasted for 6 months. Menstrual symptom scores improved significantly. AQLB may serve as an alternative option for the long-term treatment of primary dysmenorrhea.