We report a case of acute myeloid leukaemia (AML), FAB classification M2, associated with tetrasomy 8. This chromosomal aberration was detected using conventional cytogenetics and flourescent in-situ hybridization (FISH). Using FISH, the pre-treatment cells with tetrasomy 8 were disomic for chromosome 7. A small number of tetrasomy 8 cells were found post-treatment, but these were tetrasomic for chromosome 7. The significance of this is considered, and the literature regarding tetrasomy 8 in acute myeloid leukaemia is reviewed.