Peripheral neuroectodermal tumors include the differentiated neuroepithelioma and the undifferentiated Ewing's tumor. Despite clinical and pathological differences, both malignancies are characterized by a t(11;22)(q24;q12) translocation which is observed in > 90% of the cases. Molecularly, the translocation is underlaid by a rearrangement between the EWS and Fli-1 genes on chromosomes 22 and 11, respectively. Because of the difficulties in the differential diagnosis between various small round cell tumors of childhood, including Ewing's tumor, a molecular diagnostic assay would be desirable. A prerequisite for predicting the reliability of such a test resides in the molecular elucidation of the peripheral neuroectodermal tumor cases which do not exhibit the prototypical translocation. We have analyzed one such case of Ewing's tumor-derived cell line with a t(11;22;14)(q24;q12;q11) translocation. An EWS-Fli-1 fusion transcript was evidenced by polymerase chain reaction amplification of a reverse transcription product obtained from total RNA. Direct sequencing was performed to demonstrate that the molecular rearrangement in this particular Ewing sample resulted in a fusion transcript similar to those observed in tumors with the prototypical translocation.