Using probes located between 12p12.1 and 12p13.3, we performed fluorescence in situ hybridization (FISH) analysis and identified an inv(12)(p13.1q11) in a patient with acute myeloid leukemia (AML-M6). Standard cytogenetic analysis had identified the rearranged chromosomes 12 as del(12) (p11p13). Although deletions and translocations involving band 12p13 are fairly common chromosomal abnormalities observed in a broad spectrum of hematologic malignancies, inv(12) is a rather rare abnormality. We compare the clinical and cytogenetic findings with those of the previous cases reported in the literature.