A 7Z-year-old man with increased monocytes and eosinophils in the bone marrow was found to have an isochromosome, i(14q), as the safe abnormality on bone-marrow cytogenetics. Follow-up over 12 months with repeat cytogenetic testing of bone marrow specimens on three further occasions showed on additional abnormality consisting of an apparently balanced translocation, t(6;21)(p21.1;q22). This abnormality, together with other features, indicated disease progression. A review of seven reported cases of i(14q) revealed limited follow-up information. (C) Elsevier Science Inc., 1988.