Klebsiella is an encapsulated bacillus, a member of the family Enterobacteriaceae. Klebsiella can cause various illnesses, including pneumonia, bloodstream infections, urinary tract infections, and meningitis. Klebsiella has emerged as a nosocomial pathogen, particularly in premature infants and intensive care units (ICUs). This experiment aimed to investigate the toxic effects of K. pneumoniae on blood pictures and DNA structure. Thirty (30) male rabbits were divided into three groups. 1^st group (GI) was given 1 milliliter /animal an oral dose of phosphate buffer saline (PBS) by a stomach tube as a control group for 60 days. The 2^nd group (GII) was given one dose a week of 1 milliliter containing viable K. pneumoniae (1 X 10⁶ CFU/ml) orally by stomach tube for 60 days. The 3^rd group (GIII) was given the same dose twice a week. After 60 days, blood samples were collected from the heart and divided into 2 parts: 1^st part for hematological analysis and 2^nd part for detection of DNA damage using comet assay. The results of the hematological analysis showed significantly decreased RBCs, Hb and PCV, and considerably increased WBCs, lymphocytes, monocytes and neutrophils in the 2^nd and 3^rd groups, compared with the control group. In contrast, the comet assay showed DNA damage in the WBC of the different groups. The mean ± SE of tail length, tail intensity, tail moment and % DNA in the tail showed significant increases in the 2^nd and 3^rd groups, compared with the control group.