Changes in erythrocyte (RBC) polyamines were studied during total parenteral nutrition (TPN) in 16 colorectal carcinoma patients and six patients with noncancerous diseases. RBC putrescine (PTC), spermidine (SPD), and spermine (SPM) were analyzed before and at the completion of preoperative TPN in each patient. Before TPN, nutritional status, based on a history of weight loss and plasma albumin, prealbumin and retinol-binding protein levels, were similar for the two groups. Initial RBC PTC, SPD, and SPM levels were also similar for both groups. Preoperative TPN induced significant increases in RBC PTC levels (P less than 0.001) and RBC PTC:SPD ratios (P less than 0.005) of the cancer patients while no significant polyamine changes were observed in the other group. Host response to nutritional therapy was monitored with plasma prealbumin and retinol-binding protein levels which did not change significantly in either group.