It is known that, following radiotherapy, secondary cancer may occur after a long latent period. Few cytogenetic studies have been reported on tumors of the central nervous system occurring after radiotherapy. We report the cytogenetic study of six cases of radiation-induced meningiomas. In all cases, we observed the same chromosome abnormality, der(1)(1qter-->1p11::22q12-->22pter). SKY and CGH techniques allowed us to identify the chromosomal abnormalities. We suggest that a gene localized on 1p13 is involved in radiation-induced meningiomas.