Abstract: This study aimed at assessing the impact of pulmonary tuberculosis on leukocytes (count and differential) in patients living in Port Sudan city, Red Sea state, Sudan. This is a case control study covers the period from June 2006 to December 2008 at Port Sudan Tuberculosis Diagnostic Center. Hundred newly discovered, Ziehl Neelsen stain positive, males (77%) and females (23%) were randomly selected to be the study sample and fifty, apparently healthy adults males (76%) and females (24%) were also randomly selected to be the control group of the study. The ages of the patients ranged from 14-70 years old. The ratio of males to females was 3.3:1. Monocytosis was seen in (39%) of patients while (82%) of patients showed features of left shift granulocytes. Therefore, the presences of such haematological peripheral blood changes may predict raise the suspicion of pulmonary tuberculosis.