Hymenal atresia – and its results in fact - is the rare cause of pelvic or abdominal pain in pubescent girls, which could be changed for surgical cause of ailment easily. Gynecologic examination should be a part of a diagnostic algorithm in women and young girls before every surgical intervention - we can avoid an abdominal operation in case of hymenal atresia. This case report demonstrates a surprising finding in 15 years old girl, which was primarily operated by surgeon for diagnosis „acute appendicitis“. In this particular case next to clinical findings there was an extremely high value of CA 125 marker in laboratory.