The conceptual evolution in the classification of pleomorphic high-grade sarcomas is a paradigm of how the integrative morphological, immunohistochemical and molecular genetic analysis has contributed to a clinical, prognostic and therapy-oriented characterization of this complex group of tumors. The clinical and prognostic relevance of a refined subtyping of pleomorphic high-grade sarcomas, which until recently was considered a mere academic exercise, is now undisputed. It is imperative to unequivocally differentiate sarcomas from non-sarcomatous, clearly defined malignancies to start adequate therapy. Furthermore, pleomorphic sarcomas which are particularly aggressive and prone to poor prognosis, have to be separated from sarcomas which, in contrast to the pleomorphic phenotype, are characterized by a less aggressive behavior. Also, morphologically pleomorphic but benign mesenchymal tumors must be recognized. Finally, it is important to promote the promising, array-based identification of diagnostic, prognostic and clinically relevant gene signatures on larger collections of pathomorphologically and clinically precisely defined subtypes of pleomorphic high-grade sarcomas.