The authors report a case of small round cell desmoplastic tumour presenting as a testicular mass. This is a rare tumour arising from serosal tissues, especially the tunica vaginalis. It is characterized by a specific reciprocal translocation t(11;22) (p13;q12) inducing fusion of the EWS and WT1 genes. Treatment of this tumour consists of a combination of surgical resection, as complete as possible, and intensive chemotherapy (P6 protocol or Institut Gustave Roussy protocol) and possibly radiotherapy. However, the prognosis remains very poor.