Nephroptosis is a benign disorder defined as a significant descent of the affected kidney as the patient moves from supine to erect. Patients with nephroptosis sometimes manifest symptoms including abdominal pain, back pain, nausea and hematuria, while the majority of those are asymptomatic. Downward migration of the affected kidney induced by a postural change from the supine to the upright position underlies the pathophysiology of nephroptosis. The diagnosis of nephroptosis is difficult since routine imaging examinations are conducted in the supine position alone. Here, we report a case presenting recurrent abdominal pain due to unknown causes. This patient was successfully diagnosed as nephroptosis by ultrasonography and drip infusion pyelography, both of which were performed in both supine and upright positions. This case report strongly suggests that we need to take into consideration a possibility of nephroptosis when we encounter with patients complaining abdominal and/or back pain due to unknown causes.

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