We present a case of myeloid metaplasia with myelofibrosis (MM/MF), with tetrasomy 8 as the sole cytogenetic abnormality detected by conventional cytogenetic studies. Tetrasomy 8 was also detected by in situ interphase studies and confirmed by chromosome painting in metaphase. To our knowledge, this is the first case of MM/MF with tetrasomy 8. Noteworthy is the association with neurofibromatosis.