Colloid cysts are benign intracranial tumours usually occurring in the front part of the third ventricle. Clinical presentation may be non-specific and heterogeneous. The problems are frequently associated with development of hydrocephalus, these cysts may cause. We describe three cases of patients with diverse clinical symptoms, who underwent surgery for colloid cysts of the third ventricle. In the first patient, the colloid cyst caused a sudden deterioration of consciousness due to an acute hydrocephalus. The cyst in the second and third patient was discovered accidentally, during the course of epileptic seizures treatment and due to chronic headache with quanti- and qualitative deterioration of consciousness in the setting of chronic hydrocefalus, respectively. Surgery improved health in all three patients.