The t(1;22)(p13;q13) is a nonrandom chromosomal abnormality in acute leukemia with the fusion oncogene, RBM15-MKL1 (OTT-MAL), identified recently. However, this abnormality has been described only in infants and young children with acute megakaryoblastic leukemia (AMKL). We report a 59-year-old male patient with the diagnosis of acute myeloid leukemia, subtype M1, who harbors an abnormal chromosome +der(1)t(1;22)(p13;q13). The RBM15-MKL1 (OTT-MAL) fusion transcript was also confirmed by the reverse transcriptase–polymerase chain reaction. This unusual abnormality is rare in adult cases of leukemia, and in children it is restricted to AMKL. This report is accompanied by a review of the literature on the t(1;22)(p13;q13). Am. J. Hematol. 79:43–45, 2005. © 2005 Wiley-Liss, Inc.