Multiple myeloma is a disease that primarily affects the elderly, with the average age upon diagnosis being 70. Multiple myeloma (MM) is a neoplastic proliferation of plasma cells characterised by monoclonal immunoglobulin overproduction and penetration into bone and other tissues. Ascites can develop in patients with peritoneal cancers, both lymphoproliferative and solid. Ascites, on the other hand, is unusual in MM and is rarely the first indication or symptom. Ascites can develop as a result of peritoneal infiltration or as a result of liver involvement, heart failure, or kidney failure. In MM, ascites indicates a more aggressive stage, and the prognosis is dismal, with a median survival time of 1–2 months. We reported a rare case of MM in a young man who presented with renal failure and ascites and was identified retrospectively by kidney biopsy. evaluation in a patient of renal failure and ascites with kidney biopsy bringing major turning point. Since one month, a 38-year-old man has had a low-grade fever, stomach pain and distension, and decreased urine output. We present a case of Multiple Myeloma in a young man who presented with renal failure and ascites and was identified retrospectively by kidney biopsy. The need of evaluating ascites, which can be caused by Multiple Myeloma, is highlighted in this case.