AIM: Prolactinoma is a pituitary adenoma that secretes prolactin. Approximately 40% of all pituitary adenomas are prolactinomas. According to size, they are divided into micro, macro and giant prolactinomas. In women, prolactinomas cause irregularities of the menstrual cycle such as amenorrhea, galactorrhea, weight gain, in both sexes they cause sterility, hypogonadism, decreased libido and depression. In macroadenomas, symptoms due to the compression of the surrounding structures are also manifested, such as headache, vomiting, lower chiasmatic syndrome and ophthalmoplegia. Loss of the visual field due to compression of the optic chiasm is caused by a tumor larger than 10-15 mm with suprasellar spreading, which breaks through the diaphragma sellae. Giant prolactinomas are larger than 40 mm and make up 1-5% of all prolactinomas. CASE REPORT: In this article I present the case of a 38-year-old woman from Ukraine with advanced chiasmatic syndrome caused by a giant prolactinoma. The tumor is infiltrating the left cavernous sinus, causing left-sided amaurosis and right-sided temporal hemianopsia. CONCLUSION: Inferior chiasmatic syndrome is characterized by bitemporal hemianopsia, a deterioration of visual acuity, bilateral bow-tie descendent atrophy of the optic nerve disc, and hemianopic rigidity of the pupils. Macroprolactinomas occur more frequently in men than in women. The diagnosis is often delayed, probably because the symptoms of hyperprolactinemia are less obvious in men, while women tend to present earlier due to menstrual cycle irregularities. Prolactinomas usually have a good prognosis. Effective medical treatment with dopamine agonists is available. Knowledge of the prolactinoma symptoms could help the diagnosis of compressive lesions of the optic chiasm.