Purpose: Loss of heterozygosity and chromosome abnormalities usually leading to partial or total loss of chromosome 11, have been extensively described in breast and ovarian cancers. Herein we present cytogenetic findings from 5 patients (3 with ovarian and 2 with breast cancer) all showing strucutral and numerical anomalies affecting chromosome 11. This study provides further cytogenetic evidence for the localization of potential metastasis tumor suppressor genes related to breast and ovarian malignancy.