Angiosarcoma is the most common malignant neoplasm of the heart. However, to the authors' knowledge, no cytogenetic study of cardiac angiosarcoma has been reported. In the current study, an angiosarcoma from the right atrium of a 29-year-old man was investigated. Examination of tissue sections indicated that the tumor was a high grade epithelioid angiosarcoma of the heart. Cytogenetic analysis of tumor cells revealed a hyperdiploid clonal population with chromosomal numerical changes and one structural rearrangement, which was defined as: 55, XY, +der(1;17) (q10:q10), +2, +7, +8, +8, +19, +20, +21, +22. Multicolor fluorescent in situ hybridization on paraffin-embedded tissue sections illustrated polysomy of chromosome 8 in tumor cells. In addition, immunohistochemical analysis showed high expression of mutated p53 gene products in tumor cell nuclei. These findings demonstrate the involvement of chromosomal anomalies and gene mutation in cardiac angiosarcoma and suggest they play a role in neoplasia of the heart.