Acute basophilic leukemia has recently been included into a revised classification of acute leukemias proposed by the WHO panel. Due to the rarity of the disease, consistent diagnostic criteria are lacking. We report on two cases of acute basophilic leukemia that occurred in our department during the last 10 yr. We focus on their clinical, morphological and cytogenetic presentation. Both patients were >60 yr of age, and presented in good clinical condition with alterations to their full blood count. None had cutaneous symptoms such as erythema or urticaria. Cytogenetic analyses in the first patient showed a normal karyotype, while the second displayed a translocation t(2;6); (q23?4;p22?3), as well as a del (12)(p11). Earlier observations have linked bone marrow basophilia either to a deletion of the short arm of chromosome 12 (p11-13), to translocations involving the long arm of chomosome 6 at 6q23 or to the translocation t(6,9); (p23;q34). However, other translocations involving chromosome 6p23 have not been described before. Treatment of our patients consisted of supportive treatment in the one with normal karyotype and aggressive chemotherapy in the other patient. Both patients died within one year after diagnosis due to progressive or recurrent leukemia.