We report the cytogenetic findings in a case of nodular fasciitis of the breast. The abnormalities found in all 11 metaphases available for analysis were −2, −2, −1,der(15)t(2;15)(q31;q26), +der(?) t(?;2), +mar1, +mar2. Other consistent abnormalities were also identified. Fluorescence in situ hybridization (FISH) was used to confirm the origin of some of the chromosomes. A large acrocentric chromosome was confirmed to be derived from chromosome 15 with chromosome 2 material translocated onto the q arm. The metacentric der(?)t(?;2) was demonstrated to have part of chromosome 2 on the q arm. No other chromosome 2 material was found. Eight of 11 cells were tetraploid and had two copies of a del(6)(q16q24).