ÖZET Amaç: Endoskopik incelemeler; tarama, tan›, tedavi, takip amaçlarla yap›lmaktad›r. Alt gastrointestinal sistem (G‹S) endoskopisi günümüzde tan› ve tedavi amac›yla yayg›n kullan›lan bir yöntemdir. Üst G‹S endoskopiden fark›, iflleme yönelik haz›rl›k sürecinin zorlu¤u ve barsak temizli¤inin yetersizli¤i nedeniyle ifllemlerin tekrar edilmesidir. Bu çal›flmam›zda, endoskopi ünitemizde alt G‹S'e yönelik incelemelerde baflar›s›zl›k nedenlerini irdeleyerek, bu oran› azaltma konusunda yap›labilecekleri inceledik. Materyal ve Metod: Vak›f Gureba E¤itim ve Araflt›rma Hastanesi endoskopi ünitesinde Ocak 2003-2010 Ocak ABSTRACT Purpose: Endoscopic examinations are done for several purpose like to diagnose, treat and follow. Nowadays, lower GIS endoscopy is the common method which is used for diagnose and treatment. The differences of upper GIS endoscopy are that the preperation to procedure was more difficult and sometimes repeated procedures were needed because of insufficient bowel cleaning. In this article, we studied failure causes and what we can do about decreasing this failure rate in lower GIS examinations in our endoscopy unit. Material and Methods: 13595 lower gastrointestinal endoscopy studies performed between January 2003 and