The colloid cyst of the third ventricle is a benign dysembryoplastic tumor, very rare, representing 0.2 to 2% of brain tumors. It is a tumor mainly of adults in their 30s and 40s, with a male predominance. It is a rounded cystic lesion, a few millimeters to several centimeters for the largest, containing a gelatinous substance more or less liquid. The main symptom is HTIC. Many colloid cysts are asymptomatic and are discovered incidentally. MRI is the best examination to diagnose this pathology. The treatment is surgical, the therapeutic modalities are multiple, its removal without postoperative morbidity must be the rule.