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Incidental renal masses are commonly identified in routine ultrasound scanning. When focal renal lesions are identified, the most critical diagnostic questions to address are assessment of the nature and the potential clinical significance of these lesions. The majority of these are renal cysts with the biggest proportion being simple cysts requiring no active management. They may be seen in up to 50% of patients in the age group 70 years and above. Current radiological evaluation of cysts uses the Bosniak criteria for classification. While the initial classification was based on CT2 with modifications proposed and used to further refine the classification, there is an increased use of ultrasound to characterize indeterminate and incompletely characterized cystic lesions identified on CT and MRI5,6. On ultrasound, the features evaluated in a cyst include presence of posterior acoustic enhancement, presence of debris, focal wall thickening including nodules, septations and their nature (number, regularity, and thickness) and the demonstration and characterization of vascularity and blood flow. There is an increased amount of interest in the use of CEUS (contrast enhanced ultrasound) to increase diagnostic confidence and further characterize these lesions. This is of importance especially in patients who cannot receive contrast enhanced CT or MRI due to logistics, expenses and medical reasons preventing their use.