A Robertsonian balanced translocation of two D chromosomes was found in the bone marrow cytogenetic studies of a 70-year-old myeloproliferative disorder (MPD) woman. G-banding studies showed the translocation involved a 13q14q. An identical balanced t(13q14q) chromosomal pattern was found in her peripheral blood 3 years before the diagnosis of MPD as part of an investigation involving her daughter's reproductive difficulties. Her daughter is also a t(13q14q) balanced translocation carrier. The finding of a t(13q14q) in MPD may be coincidental or it may be predisposing to the development of MPD. Additional studies may elucidate this controversy.