We evaluated the role of pretreatment cytogenetics in patients with untreated mantle cell lymphoma (MCL). Patients with >= 3 chromosomal abnormalities had inferior progression-free and overall survival and had more high-risk clinical features. The effect of cytogenetics merits further evaluation in prognostic assessment in MCL. Background: Pretreatment cytogenetics are not routinely used to predict patient outcomes in mantle cell lymphoma (MCL). Based on the prognostic utility of cytogenetics in other diseases, we reviewed the effect of a complex karyotype (CK) in MCL. Patients and Methods: We included patients evaluated between November, 2002, and May, 2011. Those with >= 3 chromosomal abnormalities on a pre-treatment cytogenetic evaluation were defined as CK. Demographic, clinical, and survival differences between patients with OK and non-CK (NCK) were assessed. Results: Of 80 patients, 32 (40%) had CK, which was associated with high-risk clinical risk factors. Therapy did not differ between the groups, nor did rate of autologous stem cell transplant (ASCT). The 2-year progression-free survival (PFS) estimates were 70% and 48% for patients with NCK and OK, respectively (P = .02). Two-year overall survival (OS) estimates were also greater in those with NCK versus CK (85% vs. 58%; P = .02). When controlling for high-risk Mantle Cell Lymphoma International Prognostic Index (MIPI) score (P = .006), bulky disease (P = .01), and ASCT in first remission (P = .01), CK was not significantly associated with PFS (P = .18). Conclusion: CK is associated with shortened PFS and OS in MCL but has not been demonstrated to be prognostic independent of other variables in this series. (C) 2015 Elsevier Inc. All rights reserved.