Objective: Nuclear factor kappa B (NF-κB) is an important transcription factor in cancer and NF-κB activation has been seen in angiogenesis, tumor progression, and metastasis. Relationships between specific NF-κB gene networks, leukemogenesis, and radiation exposure are still unknown. Our aim was to study the expression levels of the NF-κB1, NF-κB2, and Rel genes in hematological malignancies in the post-Chernobyl period. Materials and Methods: We analyzed gene expression levels of NF- κB1, NF-κB2, and Rel in 49 B-cell chronic lymphocytic leukemia, 8 B-cell non-Hodgkin’s lymphoma, 3 acute myeloid leukemia, 3 chronic myeloid leukemia, 2 hairy cell leukemia, 2 myelodysplastic syndrome, and 2 T-cell large granular lymphocytic leukemia patients using realtime polymerase chain reaction. Results: Expression levels of NF-κB1, NF-κB2, and Rel genes were found to be deregulated. Conclusion: These results could be accepted as specific gene traces to radiation-induced leukemia or as potential candidates for new diagnostic biomarker studies. Larger experiments and non-exposed control malignant cell populations are needed to clarify these suggestions.