The widely accepted image of breast cancer with non-inflammatory skin involvement (T4b) is determined by the tenet that all these tumors are locally advanced (Stage IIIB). The study addresses the question whether this view is justified. Data from 453 non-metastatic breast cancer patients were collected retrospectively. Eighty-one patients had T4b disease. To assess the malignant potential of tumors independent of the feature skin involvement, a reclassification only considering tumor size was undertaken. We compared the clinical course of three study groups (A: Stage II; B: Stage IIIA; C: Stage IIIC) with control groups of 372 patients without skin involvement. In the study groups, we found a broad distribution among the stages (A:36.2%; B:33.7%; and C:27.7%) with significant differences in disease-specific survival (DSS) (A/B: p = 0.032; B/C: p = 0.048). There were no significant differences in DSS between the study and the corresponding control group. In multivariate analysis, skin involvement was not a significant predictor of DSS. Heterogeneity of the T4b category and a lack of prognostic significance expand the widely accepted image of breast cancer with non-inflammatory skin involvement. The highest T category, or Stage III, is not the appropriate classification for a considerable number of patients having this clinicopathologic entity.