One of the most frequent kidney pathologies encountered in daily practice is represented by the presence of renal cysts. Most of them are asymptomatic and are found accidentally during periodical check-ups because they don’t have clinical signs until they grow and compress the surrounding organs. We have reviewed the current data regarding this pathology, in order to underline the risk of malignant transformation and its impact on the patient’s life. It is estimated that the prevalence rate of renal cysts in the general population is approximately 10% and it increases with age.Imaging investigations, such as contrast tomography or magnetic resonance imaging, are essential for establishing the cysts characteristics, especially when ultrasonography raises the suspicion of a modified renal cyst, as well as in guiding the therapeutical protocol. The Bosniak classification is based on contrast tomography scans and has allowed the standardization of the kidney cysts, considering their characteristics. More attention should be given to Bosniak IIF and III cystic renal masses, which contain thickened walls and more septa, but no enhanced nodules/soft tissue components, because more than half of these cysts can have a malignant component