Gadolinium-containing magnetic resonance imaging (MRI) contrast agents have been reported to induce nephrogenic systemic fibrosis in patients with renal dysfunction, and therefore their use has been restricted. However, even without contrast agents, MRI can provide much valuable information on the pathophysiology of renal diseases. This report describes the case of a 90-year-old man with a hydronephrotic and dysfunctioning right kidney induced by testicular cancer evaluated by non-contrast MRI. He was referred to our hospital complaining of lower abdominal distention and appetite loss. Physical examination revealed a painless enlargement of the right scrotum and inguinal lymph node. Laboratory analysis revealed renal dysfunction, after which a non-contrast MRI was performed. T1-, T2-, and diffusion-weighted images (T1WI, T2WI, and DWI, respectively) revealed carcinoma of the right testicle with extensive multiple lymphadenopathy. Moreover, a retroperitoneal metastatic tumor was detected adjacent to the right kidney, which appeared to constrict the right urinary duct. An enlarged right kidney with loss of corticomedullary differentiation was observed on T1WI. The right kidney and enlarged renal pelvis were observed as large signal intensity areas on T2WI. DWI showed an increased signal intensity of the right kidney and a decreased apparent diffusion coefficient. These findings clarified that the retroperitoneal metastasis from the right testicular cancer led to hydronephrosis and dysfunctioning of the right kidney. The present case indicates that non-contrast MRI is useful for the evaluation of renal diseases even in elderly patients with renal dysfunction.