Adenomyosis is a benign disease of reproductive age in women characterized by the presence of endometrial tissue lesions within the myometrium. The exact mechanism of adenomyosis is not yet fully understood, although there are several theories. The clinical picture is characterized by an enlarged uterus visible on ultrasound, heavy and painful menstrual bleeding, which can lead to anemia and, less often, dyspaurenia. The diagnostic process starts with a detailed medical history and an insight into the patient's condition. In the past, the diagnosis of adenomyosis was only made after a hysterectomy, where the actual cause of the disease was removed and we gained a direct insight into the condition of the uterus. Today, with the advances in diagnostic imaging, we diagnose adenomyosis with transvaginal ultrasound and magnetic resonance imaging, where we see the changes specific to adenomyosis. A rough classification includes focal and diffuse forms, although adenomyosis can be classified by the depth of infiltration of the lesions into the myometrium, and by number of lesions. The treatment of adenomyosis includes a comprehensive and personalized approach for the patient depending on her age and taking into account the preservation of fertility in younger patients. The therapy includes various pharmacological agents from those that only relieve symptoms to those that affect the process within the lesion. We also use surgical techniques, which include radical hysterectomy, as well as some less invasive procedures to preserve fertility.