The cell line ARH77 is derived from a patient with plasma cell leukemia and has a complex and continually evolving karyotype. It is frequently used in biological studies of myeloma and plasma cell leukemia, so accurate characterization of the genome is valuable. Here we present a detailed cytogenetic investigation using G-banding and multicolor fluorescence in situ hybridization (M-FISH) in association with assessment of copy number alterations (CNAs) throughout the genome using array-based comparative genomic hybridization (aCGH). In addition to providing an accurate description of the karyotype, this complementary approach highlighted the relative merits of the individual techniques. Conventional cytogenetics and M-FISH indicated the location and types of the major chromosomal changes, whether balanced or unbalanced, and at the same time demonstrated the level of karyotypic evolution between cells. The aCGH profiles reflected the unbalanced chromosomal abnormalities detected by cytogenetics, providing refinement of their genomic breakpoint locations as well as the identification of novel genomic changes. Three aCGH platforms, comprising bacterial artificial chromosome (BAC) or oligonucleotide templates, were available for evaluation. Sixteen CNAs were consistently detected by all three platforms. Novel submicroscopic CNAs ( approximately 0.4 Mb) were detected by the highest resolution platform only, whereas the clones from the BAC arrays provided locus-specific FISH probes for confirmation of CNA.