We describe two patients with myelodysplastic syndrome (MDS) and the Philadelphia chromosome (Ph). The patients were 64- and 69-year-old men who were diagnosed as having refractory anaemia with excess of blasts. During the terminal phase, the MDS evolved to myeloblastic leukaemia. Chromosome analysis showed normal karyotypes mixed with metaphases containing a classic Ph chromosome t(9;22)(q34;q11). Surprisingly, molecular studies showed breakpoint cluster region rearrangement between exons e1 and a2, compatible with a p190bcr/abl breakpoint, as observed in acute lymphoblastic leukaemia. We discuss the correlation between MDS and acquisition of the Ph chromosome, and the occurrence of p190bcr/abl in MDS.