Cytogenetic analysis was performed on 224 bone marrow (BM) of Tunisian patients with de novo myelodysplastic syndrome (MDS) at our institution from January 1993 to December 2006. According to French-American-British (FAB) criteria, there were 36% of patients with refractory anaemia (RA), 26% with refractory anaemia with excess of blasts (RAEB), 10% with refractory anaemia with ringed sideroblasts (RARS), 12% with chronic myelomonocytic leukaemia (CMML), 9% refractory anaemia with excess of blasts in transformation (RAEB-t) and 7% of unclassified MDS. A clonal chromosomal abnormality was observed in 51% of the patients. The most frequent karyotypic change was 5q- in 30 cases (13%), followed by -7/7q- in 17 cases (8%), del(12p) in 8 cases (4%), del(20q) and trisomy 8 in 7 cases each (3%), i(17q) in 2 cases (1%) and -y in only one case (0.4%). This is the first large comparative series of MDS from an Arab country, with cytogenetic analysis showing haematological and cytogenetic features similar to those of MDS population of European or mixed European-subsaharian African origin (like Brazil), but different from those seen in Eastern populations.