Brain tumors, especially malignant forms such as glioblastoma multi-form are usually difficult to diagnose and existing treatments are usually not satisfactory. Patients’ monitoring with brain neoplasms is challenging due to the complexity and risk of biopsy, as well as the low specificity and sensitivity of currently available minimally invasive diagnostic methods. Uncertainty about diagnosis and the tumor’s respond to treatment can delay further decisions that affect outcome. Therefore, there is an urgent need for the development and validation of reliable and minimally invasive biomarkers for the diagnosis and prognosis of brain tumors that could be used alone or in combination in current clinical practice. It is known that circulating microRNAs are in a stable form and are detected in human biological fluids, such as blood, urine, cerebrospinal fluid (CSF), and saliva. In this regard, circulating microRNAs are considered as new biomarkers in a number of diseases including brain tumors. The results of many studies have shown that it is possible to profile the expression of circulating miRNAs both in the CSF and in the blood of patients with brain tumors. Some specific circulating miRNAs are expressed differently in CSF while others are expressed in blood. Circulating microRNAs found in the blood can be informative in diagnosing, predicting and tracking the effectiveness of treatment for different types of tumors. However, circulating microRNAs in the blood turned out to be suboptimal for diagnosing brain tumors while the profile of circulating microRNAs in CSF promises a more accurate and specific assessment for brain tumors.