Chromosomal aberrations have been shown to significantly affect survival in multiple myeloma (MM), but few cytogenetic analyses among Japanese MM patients have been reported. Using a commercial laboratory, we performed interphase fluorescent in situ hybridization (FISH), as well as a conventional metaphase cytogenetic study (G-banding), among 106 of 131 patients between April 1997 and February 2007. Karyotype abnormalities were found in 21.2% (21 of 99 patients). Del(13q), del(17p), del(11q), t(11;14) and t(4;14) were detected by FISH in 36.0% (31/86), 24.7% (19/77), 7.6% (5/64), 18.2% (12/66) and 10.4% (7/67) of patients, respectively. The prevalence of abnormalities detected by G-banding was lower than that reported in European countries, but when compared with FISH studies, no difference was observed. Prognostic analyses of patients with these abnormal chromosomes revealed that those with abnormal karyotype and del(13q), t(4;14), as detected by FISH, had significantly poorer survival. This study suggests that the prevalence of chromosome abnormalities among Japanese patients is similar to that for European populations, and that chromosome studies by G-banding and FISH are essential to predict survival.