The cellular compositions of the inflammatory infiltrates in human colonic carcinoma in well-defined compartments have not been quantified previously. Morphometric analysis of this tissue revealed several relationships between the concentrations of different kinds of cells that may be an important first approach to understanding the nature of the host reaction in different groups of patients. Primary tumors without metastases differ from those with metastases in that those without metastases contain higher concentrations of plasma cells (P = 0.0019) and eosinophils (P = 0.0098) in sections taken at a location remote from the margin (tissue located greater than 1 cm from the margin) and increased concentrations of eosinophils (P = 0.0224) in sections of tumor contiguous to the margin (tissue 0-4.5 mm from the margin). In sections contiguous to the margin, the concentration of plasma cells is related to the concentrations of lymphocytes (R = 0.55, P = 0.0014), eosinophils (R = 0.46, P = 0.0085), fibroblasts (R = 0.47, P = 0.0075), and neutrophils (R = 0.63, P = 0.0001). In sections remote from the margin, the concentration of plasma cells is related to the concentration of lymphocytes (R = 0.36, P = 0.0442), eosinophils (R = 0.36, P = 0.0457), mast cells (R = 0.38, P = 0.0375), and neutrophils (R = 0.38, P = 0.0371).