The time of the first menstrual period is normal as long as it is over 11 years of age, and the average time of menstruation is 13-14 years of age. If menstruation does not occur beyond the age of 16 and there is no development of secondary sexual characteristics, amenorrhea is present. The cause of amenorrhea must be identified as soon as possible. It may be due to abnormal genital development or chromosomal abnormalities. If menstruation occurs before the age of 11, it may be precocious puberty, and the need for treatment must also be determined on a patient-by-patient basis. If the person is short, it is necessary to apply drugs that inhibit hormone secretion to prevent the healing of the epiphysis.