Cytogenetic analysis of a phyllodes tumor of low grade malignancy disclosed the karyotype 52-55,XX, -1,+5,+7,+9,+10,+11,-15,+18,-19,+20,der(21)t(1;21)(p13;q22),+mar1x 2-4,+mar2[cp18]/46,XX. This study shows that a complex chromosome karyotype can be found in low-grade phyllodes tumors and is not necessarily a sign of extreme malignancy of these neoplasms.