AbstractCytogenetic and molecular studies were performed on two dmin‐bearing acute myelogenous leukemia (FAB‐M2) samples. Both cases were characterized by complex karyotypes containing interstitial deletions of the long arm of chromosome 8 altering band 8q24.1, aberrations affecting the short arm of chromosome 17, and multiple double minute chromosomes (dmin). Using a 1.4 kb cDNA probe coding for the third exon of theMYConcogene, DNA slot blots indicatedMYCgene sequences were amplified in both samples. Fluorescence in situ hybridization using a 9.0 kb genomic probe forMYCwas performed in one we and localized the amplifiedMYCgene sequences to the dmin. Neither patient achieved a complete remission using traditional induction chemotherapy. The complex karyology with amplification ofMYCgene sequences appears to represent a poor prognostic subgroup of acute myelogenous leukemia.Genes Chrom Cancer 9:62‐67 (1994).© 1994 Wiley‐L