Menstrual patterns can be an indicator of overall health and self-perception of well-being. Primary amenorrhea, defined as the lifelong absence of menses, requires evaluation if menarche has not occurred by 15 years of age or three years post-thelarche. Secondary amenorrhea is characterized by cessation of previously regular menses for three months or previously irregular menses for six months and warrants evaluation. Clinicians may consider etiologies of amenorrhea categorically as outflow tract abnormalities, primary ovarian insufficiency, hypothalamic or pituitary disorders, other endocrine gland disorders, sequelae of chronic disease, physiologic, or induced. The history should include menstrual onset and patterns, eating and exercise habits, presence of psychosocial stressors, body weight changes, medication use, galactorrhea, and chronic illness. Additional questions may target neurologic, vasomotor, hyperandrogenic, or thyroid-related symptoms. The physical examination should identify anthropometric and pubertal development trends. All patients should be offered a pregnancy test and assessment of serum follicle-stimulating hormone, luteinizing hormone, prolactin, and thyroid-stimulating hormone levels. Additional testing, including karyotyping, serum androgen evaluation, and pelvic or brain imaging, should be individualized. Patients with primary ovarian insufficiency can maintain unpredictable ovary function and may require hormone replacement therapy, contraception, or infertility services. Functional hypothalamic amenorrhea may indicate disordered eating and low bone density. Treatment should address the underlying cause. Patients with polycystic ovary syndrome should undergo screening and intervention to attenuate metabolic disease and endometrial cancer risk. Amenorrhea can be associated with clinically challenging pathology and may require lifelong treatment. Patients will benefit from ample time with the clinician, sensitivity, and emotional support.