Desmoid tumors are benign neoplasms of the fibromatosis group. Data on their acquired chromosomal changes are sparse and, therefore, we wanted to ascertain what genomic losses and gains these tumors may have incurred. DNA was extracted from a total of 26 formalin-fixed, paraffin-embedded desmoid tumors followed by comparative genomic hybridization (CGH) and interphase fluorescence in situ hybridization (I-FISH) analyses. Ten of 12 informative tumors were normal by CGH; the two abnormal ones had loss of chromosome 6 and loss of 6q and gain of chromosome 20, respectively. I-FISH analyses with an alpha-satellite probe specific for chromosome 8 of 26 desmoids, including one tumor that by karyotyping had +i(8)(q10), showed no evident abnormalities. An explanation for the relatively high frequency of genomically normal tumors by CGH seen in this study may be sought in the fact that as many as 10 of the 12 informative tumors were abdominal desmoids, a subset of tumors also previously found to exhibit genomic changes only rarely. It is therefore possible that abdominal desmoids might be non-neoplastic tumors or neoplastic tumors with genetic changes too small to be discovered by CGH, whereas desmoid tumors from other locations exhibit detectable genomic changes at a significantly higher frequency.