This study conducted to investigate sub clinical mastitis caused by some coliform pathogens as a common causes mastitis in the cows and to detect some hematological & biochemical parameters, for this purpose 100 milk samples and100 blood samples were collected from apparently cows brought to the veterinary hospital & from different heifer’s in Kirkuk governate, Iraq. our results showed that the incidence of coliform mastitis by using different diagnostic methods. the incidence mastitis to CMT according of management & hygiene milk of processing recorded 35 (42.6 %), 47 ( 57.3%) respectively., However the bacteriologically examination depending on isolation, biochemical manually and vitek system identification. revealed, the incidence as 82.9% positive for bacterial identification reveled that E.coli was predominant ( 33.8 %) bacteria Followed by K. pneumonia and. Proteus mirabilis (11.7 %) &(10.2)% respectively. further hematological parameters we noted that showed anemia with significant decrease (p<0.05) in Hemoglobin, Total red blood cell count, Paced cell volume, lymphocyte and slightly decrease in, while record increase in granulocyte and Wight blood cell count. On the other hand the biochemical profile we showed significant increase in ALT, AST enzymes, While decrease significant(p<0.05) in ALP, Ca, Cl, P, Mg & zn. We conclude from this study, The prevalence of pathogenic bacteria in the milk resulted in a significant alteration in the hamato-biochemical profile in the current study reveled significant monitors for Bovine mastitis and estimate the efficiency and quality of milk consumption.