There is abundant evidence that intermediate filaments can be used as cell type specific markers both for normal tissue and for tumors. The results of intermediate filament typing in soft tissue tumors and its diagnostic relevance is shown. This system can also be used to solve other problems in surgical pathology. One of the most useful applications of intermediate filament typing is to differentiate the round cell tumors of children; thus, rhabdomyo-sarcomas are desmin positive, malignant lymphomas contain only vimentin, and neuroblastomas show positivity for neurofilaments.