Oncogenes have been implicated in the promotion and progression of cancer in humans. Expression of the ROS1 oncogene, a member of the receptor tyrosine kinase superfamily, was examined in human meningiomas by coupled reverse transcription and polymerase chain reaction (RT-PCR) assays. Two sets of region-specific oligonucleotides, specific for different regions of the ROS1 messenger ribonucleic acid (mRNA), were used in RT-PCR assays to independently examine ROS1 transcripts from primary human meningiomas. ROS1 was expressed at high levels in approximately 55% (17 of 31) of the meningiomas examined, but not expressed in non-neoplastic brain samples. The commonplace expression of the ROS1 oncogene in meningiomas suggests a role for this oncogene in the etiology of these tumors.