Infection is a life threatening complication in patients with hematological malignancy. So, proper treatment of infection with suitable antibiotic is very important in these patients. The aim of this study was to determine the antibiotic susceptibility of bacteria isolated from various specimens of patients with hematological malignancy, so that, an appropriate regimen of empiric antibiotic treatment can be established for these patients. This observational study was done in the Department of Microbiology and Immunology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from March 2012 to August 2012. Forty (40) diagnosed patients of hematological malignancies who were admitted in the Department of Hematology and Paediatric Hemato-oncology, BSMMU with symptoms of sepsis &/ or urinary tract infection (UTI) or respiratory tract infection (RTI) were enrolled in this study. Blood, throat swab and urine were collected from each patient and sputum was collected from four patients. Susceptibility pattern of Gram positive bacteria to antibiotics was satisfactory. But Gram negative bacteria were resistant to commonly used antibiotics. Enterobacteriaceae group of organisms were found completely resistant to Ceftriaxone & Aztreonam. The best drugs for them were Imipenem, Amikacin & Netilmicin. P. aeruginosa & Acinetobacter spp. were completely resistant to several antibiotics including Cephalosporines & Ciprofloxacin. The best drug for them was Imipenem, Netilmicin & combination of Tazobactam & Piperacilin.