Tumorigenesis of meningioma has been associated with chromosome 22, most notably the NF2 gene, but additional genes have also been implicated in meningioma development. Previously, we have cloned the cDNAs for the meningioma expressed antigen 6 (MGEA6) and its splice variant MGEA11. Here, we show that antibodies against recombinantly expressed MGEA6/11 are found in 41.7% (10/24) of the sera from meningioma patients and in 2/8 sera of glioblastoma patients, whereas no response was seen in 12 sera from healthy persons. Western-blot analyses using generated polyclonal antibodies, revealed overexpression in meningioma and glioma tumor samples compared to normal brain. Immunohistochemical staining of tissue sections confirms reactivity in meningioma tumor cells and tumor cells of glial origin. We found no reactivity to normal astrocytes and only faint reactivity to normal leptomeninges. Sequence analysis predicted membranic localization of MGEA6/11, that was confirmed by cell fractionation. The immune response to MGEA6/11 is frequent in both meningioma and glioma patients and may likely be attributed to overexpression of the MGEA6/11 protein in the tumor cells.