Identification of the SYT-SSX fusion transcript can be a useful diagnostic aid for synovial sarcoma. However, there is no report on the detection of the specific transcript in archival cytologic specimens. We performed a rapid reverse transcription-polymerase chain reaction assay to detect the fusion transcript using such specimens as RNA sources and compared its usefulness with the assay using formalin-fixed paraffin-embedded histologic specimens. Eleven cytologic and 12 histologic specimens stored for 0.1 to 20 years were selected from 9 patients. The SYT-SSX transcript was identified in 10 (91%) of 11 of cytologic and 9 (75%) of 12 histologic cases. One of the transcript-positive cytologic cases was obtained by fine-needle aspiration. SYT-SSX1 fusion was found in 4 patients and SYT-SSX2 in 5. Cytologic specimens will be an excellent RNA source for the reverse transcription-polymerase chain reaction diagnosis of synovial sarcoma with a sensitivity of more than 90%, comparable to that in frozen materials. Histologic materials also may be useful when cytologic or frozen materials are not available.