Pancytopenia is defined by reduction of all three formed elements of blood below the normal reference . It may be manifestation of a wide variety of disorders , yet there exist few published assessments of the frequencies of various etiologies , and these frequencies exhibit substantial geographic variation . This study was carried out to investigate for and to identify the causes of pancytopenia , to find out the frequency of different causes , to determine the incidence of pancytopenia in relation to sex and age and to compare our findings with those of other similar studies in different countries .This was a prospective study conducted in Al-Asad and Tishreen academic hospitals in Lattakia city , Syria , ovar a period of one year . A total of 113 patients with the diagnosis of pancytopenia were enrolled in the study All patients underwent a detailed medical history and full physical examination followed by blood sampling for the investigations i.e. complete blood count with peripheral film , erythrocyte sedimentation rate ( ESR ) , liver function test , PT , HBsAg and Anti- HCV , ultrasonography of abdomen . All patients underwent bone marrow aspiration and trephine biopsy for some patients. A definite female preponderance was observed , 59 were female and 54 were male. The majority of cases were encountered in the age group of more than sixty years old .Infiltration disorders were the commonest cause that was observed in 38.1% followed by infections in 22.1% , megaloblastic anemia 12.4% , myelodysplasia 11.5%, aplastic anemia 7.1% , myelofibrosis 3.5% , hypersplenism 3.5% and systemic disorders 1.8% Detailed clinical history and meticulous physical examination along with baseline hematological investigations provide good information and help in systematic planning of further investigations to diagnose pancytopenia's cause.