Haemophilia B (HB) (also known as Christmas disease) is a form of haemophilia characterized by a factor IX (FIX) deficiency leading to spontaneous or prolonged haemorrhage. It is inherited as x-linked recessive disorder which affects almost exclusively men. Depending on the nature of the genetic mutation that is the cause of the disease, the affected coagulation factor may be totally absent from the patient's organism or present but in a dysfunctional form. Different degrees of severity of haemophilia have been established: minor, moderate, severe, based on plasma anti-haemophilic factor activity. Generally, this circulating factor level correlates with observed clinical manifestations. Molecular studies of these mutations are essential to increase our understanding of their pathogenic effect causing the disorder. Nine male patients with severe HB, were enrolled in this study. DNA was extracted by the salting out method. Direct sequencing of a complete exon is possible once it has been amplified from genomic DNA with the polymerase chain reaction (PCR) technique. The HB mutation was identified by automated sequence analysis using the capillary electrophoresis method. We identified 2 point mutations (missense mutations). The first identified mutation is located in exon 4 and the second is situated in exon 8.