Mixed neuroendocrine and non-neuroendocrine type of tumor in renal pelvis is rare and presents a high-grade malignancy. We present a case report that a 57-year-old man had no history of small cell cancer but presented a high-grade neuroendocrine carcinoma with focal squamous metaplasia and multiple stones simultaneously in the right renal pelvis. The patient underwent nephroureterocystectomy 9 months before this presentation, with evidence of multiple metastatic tumors in various parts of the body. The case of mixed neuroendocrine tumor with stones in the renal pelvis carries a poor prognosis and poses a therapeutic challenge to urologists.