The t(X;18) translocation is known to be a useful marker for the diagnosis of synovial sarcoma. In this study, the authors describe a new real-time reverse transcriptase-polymerase chain reaction (RT-PCR) method to detect SYT/SSX fusion transcripts using paraffin-embedded and frozen tumor specimens. A series of 38 soft tissue sarcomas were analyzed. Diagnosis was based on clinical, histologic, and immunohistochemical examination. The fusion transcripts were detected in 16 of 17 synovial sarcoma samples (the 17th sample was not suitable for molecular analysis). No t(X;18)-fusion transcript was PCR-amplified in the 21 nonsynovial sarcoma mesenchymal tumors. Therefore, real-time PCR amplification appears to be a powerful, rapid, specific, and sensitive technique that can be used routinely to diagnose the synovial sarcoma t(X;18) translocation. In addition, the t(X;18) can be detected not only on frozen but also on paraffin-embedded tumor samples