A childhood case of myelodysplastic syndrome (MDS) with a deletion of the long arm of chromosome 5 (5q-) is reported. The patient was an 8 year old boy who has recurrent angina. Laboratory evaluation revealed the following: hemoglobin 8.1 gm/dl, white blood cell count 4.9 x 10(3)/l with 3% atypical lymphocytes, and platelet count 17.7 x 10(4)/l. A bone marrow aspirate revealed 20% blast cells and dysmyelopoietic changes involving all three marrow cell lines. Karyotype analysis of marrow cells revealed 46,XY,5q- in 100% of the metaphases. These findings led to a diagnosis of MDS with 5q-, which is most commonly found in adult MDS. This case seems to represent an exceedingly rare childhood case of MDS with 5q-.