Renal cysts are a common imaging finding. Although most cysts never have symptoms, some cause pain, collecting system compression, hematuria, hypertension, and secondary infection. The mere presence of a cyst is not an indication for intervention, but treatment may be indicated in symptomatic patients or those with secondary obstruction. Urinomas generally are a contained collection of urine outside of the normal pathways where urine travels. As such, urinomas can arise anywhere from the upper abdomen down into the low pelvis and have a variety of etiologies. Ureteral obstruction with forniceal rupture and trauma (blunt, penetrating, or iatrogenic) are the most common causes of urinomas. When urinomas arise spontaneously, the likely cause varies with the patient's age. Blunt or penetrating trauma can cause perinephric urinomas by two mechanisms—direct disruption of the pelvis or collecting system or by degeneration of nonviable tissue. These urinomas are often perinephric, but can also occur in a subcapsular location. This review will discuss diagnosis, classification, and treatment of renal cysts and urinomas.