Various diseases can arise from pelvocalyces and ureter. They are inflammation, infection, tumor, trauma, and sometimes a combination of these conditions. Ultrasonography (US) and intravenous urography (IVU) have been used in upper urinary tract diseases from the past to the present. Recently, computed tomography (CT) and magnetic resonance imaging (MRI) have been increasingly used as problem-solving methods to diagnose the upper urinary tract accurately after the other imaging modalities. CT is especially useful in diagnosing urolithiasis and other co-morbid conditions, and it is used primarily in conjunction with other imaging modalities. This chapter covers the various diseases of the pelvocalyces and ureter and their findings in imaging studies.