An 81-year-old woman was diagnosed with smoldering multiple myeloma (20% clonal plasma cells but no end organ damage) in November 2013. She was observed until December 2014 when she presented with rapid-onset ascites. No stigmata of chronic liver disease were present. A computed tomography scan of the abdomen confirmed the ascites (panel A), and Doppler studies showed normal blood flow. Alkaline phosphatase was 321 U/L, aspartate aminotransferase was 21 U/L, and international normalized ratio was 1.4. Her serum monoclonal protein was 32 g/L (immunoglobulin G [IgG]κ), IgG was 3980 mg/dL, IgA was 34 mg/dL, and IgM was 22 mg/dL. The serum κ free light chain was 49 mg/dL and λ free light chain was 0.3 mg/dL (ratio, 163). She had 38 mg of light chains in her urine. Bone marrow cytogenetics was normal, and a fluorescent in situ hybridization panel did not show any abnormalities. Multicolor flow cytometry was negative for circulating clonal plasma cells. Congo red staining of the bone marrow and abdominal fat was negative, and echocardiography was normal. Ascites fluid cytology was negative. During transjugular liver biopsy, the portosystemic pressure gradient was 17 mm Hg. The liver biopsy showed extensive infiltration of the hepatic sinusoids with κ light chain–restricted plasma cells (panel B), thus explaining her portal hypertension and ascites. Given her performance status of 1, therapy with bortezomib, cyclophosphamide, and dexamethasone was instituted.Hepatic infiltration by malignant plasma cells in a rare feature at the time of diagnosis of multiple myeloma, although it is often observed in patients with relapsed/refractory disease.