Cancer chemotherapy is responsible for infections by decreasing the phagocytosis and chemotaxis of polymorphonuclear. We conducted a retrospective analysis during the period from 18/10/2006 to 21/05/2008, on all bacteria isolated from blood cultures performed in the department of clinical hematology at the hospital military instruction Mohamed V. One hundred and sixty two blood isolates were selected; Gram positive cocci (CGP) accounted for 60.34% and Gram negative bacilli (GNB) for 24.14%. Coagulase negative staphylococci (SNA) and S. aureus presented a resistance to methicilline respectively 54.55% and 22.22%. Prevalence of Gram positive cocci is consistent with the results of the EORTC (International Antimicrobial Therapy Cooperative Group). Analysis of resistance patterns of all species, except for staphylococci, showed phenotypes essentially community, sometimes wild. In conclusion probabilistic antibiotic treatement of bacteraemia in the haematology department should focus among other staphylococci resistant to methicilline.