Aim. To characterize the clinical and hematological variability of acute myeloid leukemia (AML) with t(8;21) and to identify the signs associated with the likelihood of its relapse. Subjects and methods. The results of examining 44 patients aged 11 to 70 years were analyzed; the efficiency of treatment was evaluated in 36. Their karyotypes were studied using the standard GTG method. Polymerase chain reaction (PCR) was employed to assess the mutational status of the FLT3, NPM1, NRAS and c-Kit genes. Qualitative PCR was used to reveal the chimeric transcript RUNX1/RUNX1T1. Results. The M2 variant was verified using the French-American-British classification in 82% of cases. One patient was diagnosed with secondary AML. Additional chromosomal aberrations were found in 50% of the patients. The most common breakages were loss of one of the sex chromosomes (34.1%) and damage of chromosome 9 (16.6%). Gene mutations were detected in single cases. Following 2 7+3 induction chemotherapy (CT) cycles, complete remission (CR) was achieved in 97% of cases (3 patients with cytopenia died). Eight (25%) patients developed a relapse mainly within the first 7 months after achieving CR. The characteristic signs of relapse cases were the inefficiency of the first cycle of remission induction (RI), the absence of high-dose consolidation, damage of chromosome 9, D816V mutation in exone 17 of the c-Kit gene. Antirecurrent CT was ineffective in 5 patients. The median overall survival (OS) in patients with early recurrence was 10 months. That in the patients who were recorded to have CR was not achieved; 5-year OS was 57.8%. Chromosome 9 aberration was ascertained to have a negative impact on OS parameters (p=0.003). Conclusion. Patients with AML with t(8;21) is a group heterogeneous with respect to age, the morphological nature of blast cells, the pattern of the disease, the presence and type of additional chromosomal aberrations, mutations in individual genes, and clinical course. Those who are unresponsive to the first RI cycle and have additional chromosome 9 damages should be regarded as potential candidates for allogeneic hematopoietic stem cell transplantation.