Deletion of the long arm of chromosome 15 has been described as a recurrent chromosomal abnormality in myeloid malignancies. We present here some additional case reports of deletion 15 including two cases with an extra copy of the deleted chromosome, a finding that has not previously been described. We compare our cases to those previously reported. Our findings show that, contrary to previous reports, this abnormality may not always be associated with an unfavorable prognosis. They also indicate that deletion 15q most frequently appears to be associated with myelomonocytic disease. Potential candidate genes on 15q that may be involved in the tumorigenesis of these cases are discussed.