Refeeding of patients with malignant tumors may induce tumor-cell DNA synthesis. The present study was aimed at evaluating whether induction of altered cell-cycle kinetics could be induced by intravenous total parenteral nutrition (TPN) in tumor biopsies from head and neck cancers. Nine malnourished patients with squamous cell carcinoma in the head-and-neck area were investigated before and after 5-7 d of continuous TPN. Tumor biopsies were taken in both fasted and fed states for determination of 1) ornithine decarboxylase (ODC) activity, which is rate limiting for polyamine synthesis; 2) flow-cytometric-DNA-distribution measurements; and 3) the fraction of proliferating cells expressed as immunohistochemical reactivity with the monoclonal antibody Ki-67. The histopathological differentiation, the fraction of aneuploidic cells, ODC activity, and Ki-67 reactivity were not significantly related to each other, although the number of aneuploidic cells in replicative phases correlated with the number of cells expressing the Ki-67 antigen (r = 0.86, P less than 0.01). Tumor cytokinetics showed no evidence of being changed by TPN administration.