Here we report a rare case of Merkel cell carcinoma complicated with nephrosis and malignant lymphoma. A 79-year-old male, who had undergone rectectomy due to colorectal cancer about 10 years previously, was diagnosed as Merkel cell carcinoma of the left ear lobe with lymph node metastases. Tumor resection and lymph node dissection were performed. A year later, follow-up PET-CT revealed a small hot spot at the ileocecum without apparent tumor formation based on examination by colonoscopy. The patient received 56 Gy of radiation. Two months later, he developed new-onset nephrosis followed by renal failure, and was referred to our hospital (Cr 4.26 mg/dL, UA 13.5 mg/dL, Alb 2.1 g/dL). Further examination negated the possibility of vasculitis, collagen disease, or myeloma kidney. Since his renal function continued to decline, causing uremic symptoms, he was hospitalized and underwent hemodialysis soon after referral. Abdominal CT scan revealed an ileocecal mass with multiple abdominal lymphadenopathy, which was later diagnosed as diffuse large B-cell lymphoma (stage IV) by tumor biopsy. Corticosteroid therapy (prednisolone 60 mg/day) was soon initiated with no response. Local skin redness and blister formation at the left shoulder emerged gradually, which strongly suggested a local recurrence of Merkel cell carcinoma. Despite the use of rituximab, the patient's general condition deteriorated without any sign of recovery. Three months after the start of dialysis, we discontinued dialysis therapy due to his poor health status, and eventually he died of cachexia. Autopsy revealed triple cancers: rectal cancer, Merkel cell carcinoma, and malignant lymphoma. In addition to the case report, we will summarize and discuss former similar case reports in the literature.