RESULTS: In examined specimens the following microorganisms were identified: Klebsiella pneumoniae, Escherichia coli, Streptococcus pneumoniae, Staphylococcus aureus, Mycobacterium avium complex, Aspergillus fumigatus, Candida albicans. In elderly over 60 years, severe concomitant infectionsoccured more frequently than in younger population. In 98 patients (40,5%) the proper oncological management was delayed becouse active infection, and response to anti-cancer therapy was worse than the rest without active infection. In 180 patients (82,2%) active bactericidal or fungal infection negatively influenced on quality of live and overall survival. 25 (12,4%) patients died becouse neutropenic fever.