en Surgery Surgery case report case report Familial colloid cyst of the third ventricle is very rare. This is one of the two largest families reported and the first in which all affected members are siblings. One asymptomatic sister was found by screening, emphasizing the value of screening. A brother and two sisters from a family consisting of three brothers and three sisters who were diagnosed as having colloid cyst of the third ventricle are presented. The index case like his sister underwent a tumor resection by middle frontal gyrus approach. Brain CT scan was performed for the other first degree family members for screening and colloid cyst was detected in another sister_ When two or more members of a family are affected, screening has an important value for detecting other asymptomatic members with colloid cyst of the third ventricle. colloid cyst, third ventricle, familial. 267 269 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-152&slc_lang=en&sid=1 SOHRAB SADEGHI 20031947532846003767 20031947532846003767 No From the Dept. of Neurosurgery, Loghman-Hakim Medical Center; Shahid Beheshti University of Medical Sciences, Tehran, Iran. GUIVE SHARIFI guivesharifi@hotmail.com 20031947532846003768 20031947532846003768 Yes From the Dept. of Neurosurgery, Loghman-Hakim Medical Center; Shahid Beheshti University of Medical Sciences, Tehran, Iran. ALI ALIASGARI 20031947532846003769 20031947532846003769 No