Complex renal cysts usually refer to renal cysts combined with more abnormalities and may be at risk of malignant changes. Complex renal cysts are compared to simple renal cysts, which are spherical in shape and consist of simple cystic skin and fluid, and are usually asymptomatic. On the other hand, complex renal cysts may have calcified foci as well as segregation inside the cyst, which may be combined with bleeding, infection, etc., and even have a tendency of malignant transformation. Complex renal cysts can be clearly detected by ultrasound or CT examination. Its imaging findings are much more complex than those of simple renal cysts, and it is known as complex renal cyst or atypical renal cyst. The presence of complex renal cysts may lead to symptoms such as low back pain, hematuria, etc. Symptomatic therapeutic measures need to be taken in time, and if there is a tendency of cancerous transformation, surgical treatment is needed. If complicated renal cysts are found, it is recommended to go to regular hospitals in time and give targeted treatment or therapy under the guidance of doctors.