Ascites total protein concentration (A-TP) affects the performance of cell-free and concentrated ascites reinfusion therapy (CART). As the factors determining A-TP remain unclear, we examined peritoneal and liver metastasis. Among 98 patients who received CART, 68 with cancer, ascites from no other apparent cause, and complete CT and A-TP data were recruited. Sixty-six patients (97%) with peritoneal and/or liver metastasis on CT were divided into the peritoneal metastasis group (PM group), peritoneal and liver metastasis group (PM + LM group), and liver metastasis group (LM group). A-TP was highest in the PM group (3.9 g/dL [3.4–4.4]), lowest in the LM group (1.0 g/dL [0.9–2.0]), and broadly dispersed in the PM + LM group (3.3 g/dL [2.0–3.8]). All differences were statistically significant. The percentage of metastasis volume occupying the liver was negatively and significantly related to A-TP in the PM + LM group. Taken together, the presence and severity of peritoneal and liver metastasis may influence A-TP.