 To investigate the expression of EWS-FLI1/ERG fusion transcript resulting from t(11;12)(q24;12) in paraffin-embedded tissues and its diagnostic implication for Ewing's sarcoma/peripheral primitive neuroectodermal tumors (ES/pPNET).     ///    EWS-FLI1/ERG fusion transcript was detected in 20 of the 25 ES/pPNET cases (80%).     ///    Detection of EWS-FLI1/ERG fusion transcript is a reliable index for molecular diagnosis of ES/pPNET.     ///    "One-step reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to detect a characteristic EWS-FLI1/ERG fusion transcript in 25 cases of ES/pPNET and 15 cases of other small round cell tumors (including 8 cases of rhabdomyosarcoma, 4 cases of synovial sarcoma, 2 cases of neuroblastoma and 1 case of lymphoma) using formalin-fixed and paraffin-embedded tissues. "    ///    The 15 non-ES/pPNET control cases were negative for EWS-FLI1/ERG fusion transcript. 