Puberty as a field for specialized study has received scant attention. The amount of available clinical data applicable to this important period of life is decidedly small in comparison with the corresponding advances in other fields of medicine. The overlapping between the specialties of internal medicine and pediatrics during these years has retarded the development of intensive study of this period by either group, and this age period has been aptly called a "no man's land." The pediatrician is particularly well adapted to assume responsibility in dealing with the problems of the adolescent child as he knows the entire previous background of the child. It therefore is fitting that he should acquaint himself better with the various aspects of puberty. With these ideas in mind, we take the privilege of calling to the attention of pediatricians a condition more familiar to gynecologists, namely, hematocolpos due to imperforate hymen.