Recent progress made in the field of sarcoma biology has shed new light on the pathophysiology of these numerous but rare diseases. Soft tissue sarcomas can be divided into 6 sub-types based on the underlying molecular biology of the disease: 1) translocation leading to fusion proteins involving transcription factors or growth factors (Ewing sarcoma, myxoid liposarcoma, dermatofibrosarcoma protuberans); 2) tyrosine kinase receptor mutations (gastrointestinal stromal tumors); 3) tumor-suppressor gene deletion (type 1 neurofibromatosis, rhabdoid tumors); 4) genetic alteration such as amplification of chromosomal regions (well differentiated/dedifferentiated liposarcoma); 5) sarcomas with more complex genetic alterations (leiomyosarcoma) and 6) abnormalities involving the cell-adhesion pathways (aggressive fibromatosis). Together with the current development of numerous targeted therapies, these recent progress are the basis of tomorrow's personalised medicine for patients with soft tissue sarcoma.