The purpose of the present study was to determine if a nonmalignant skin-associated T-cell might exhibit nuclear irregularity and represent the normal counterpart to the malignant Sézary T-cell found in mycosis fungoides (MF) and the Sézary syndrome (SS). Punch skin biopsies from ten benign lymphoid infiltrates of skin were subjected to ultrastructural morphometric analysis and quantitative immunohistochemistry (on serial frozen sections) using a battery of monoclonal antibodies. Form factor (FF) (4tA/p2) was used to assess nuclear contour irregularity. The lymphoid infiltrates were morphometrically heterogeneous (range of FF values: 0.482–0.704). Immunophenotypically, there was marked variation in host response to the variety of antigens presented. Linear regression analysis was used to determine if nuclear contour irregularity showed any statistical relationship to immunophenotypically defined lymphocyte subpopulations. It was determined that nuclear contour irregularity (mean FF values) did not correlate with the presence of any surface antigen tested. This included the antigens Leu-2a, Leu-3a + b, Leu-4, Leu-6, Leu-7, Leu-8, Leu-9, Leu-14, and la. There was, however, significant correlation of increased nuclear contour irregularity with the presence of Leu-9−and Leu-8−cells (r = 0.7 and 0.6, respectively), lymphocyte subsets reportedly deficient in MF and the SS. This finding leads to the speculation that the Leu-9−, Leu-8−reactive T-cell with an irregular nucleus might represent the normal counterpart to the malignant clonally expanded T-cell found in MF and the SS. It was also determined that helper to suppressor ratios varied 68-fold from 0.2 to 13.5 among these ten benign lymphoid infiltrates of skin. This finding underscores the futility of using helper to suppressor ratios as a diagnostic tool in defining T-cell malignancies.