Aims:The aim of this study was to identify septicemia in intensive care unit (ICU) patients, determine the antibiotic resistance profiles and minimum inhibitory concentrations (MICs) of all isolates by using the Vitek-2 compact system and study some immunological parameters (IgM, IgG and hs-CRP) in ICU patients, with and without septicemia. Methodology and results: Ninety blood samples from both sexes and different age groups (ranging from 21-90 years) were collected from different hospitals in Mosul city. Twenty-four blood samples were collected from healthy people and used as a control group for the period between July and December of 2022. Samples were subjected to bacterial diagnosis, antibiotic sensitivity test using Vitek2 and measurement of some immunological parameters. The results showed that 24/90 (26.67%) of the blood samples exhibited positive cultures, with Gram-positive bacteria predominating, 14/24 (58.34%), while Gram-negative bacteria represented 10/24 (41.66%) of the positive samples. Antimicrobial susceptibility testing showed that vancomycin, linezolid, imipenem and rifampicin were mostly effective against most Gram-positive septicemia isolates, whereas meropenem, imipenem and colistin were mostly effective against most Gram-negative bacterial isolates. The ELISA results revealed elevated levels of IgM, IgG and hs-CRP in the serum of septicemia patients compared to the healthy control group, with a significant difference in P-value (0.001). In addition, the mean levels of IgM, IgG and hs-CRP in the serum of non-septicemia patients compared to the healthy control group indicated a highly significant difference in P-value (0.001). Conclusion, significance and impact of study: IgM, IgG and hs-CRP levels were significantly different in sepsis patients infected with Gram-positive and Gram-negative bacteria compared to the healthy control group.