IMNCI is the process of caring for all ill children under 5 years of age that combines preventive, promotive and curative actions for leading causes of child deaths . Training of nurses in management of IMNCI cases will provide the knowledge and skills needed to provide health services to healthy children for follow up and children suffering from range of diseases and case management, refer ill children who need urgent referral, prescribe and administer appropriate treatments and providing child caregivers with information about treatment and follow up visits. Implementation of IMNCI demonstrated progress in the quality of care provided for sick children . To evaluate the impact of reinforcement educational sessions regarding the integrated management neonatal and childhood illness on nurses knowledge. A quantitative study (quasi-experimental design) carried out for achieving the objectives of present study, by application of pre-test & post-test approach for both study group and control about nurses working in IMNCI units from 20th September 2020 to 25th April 2022. The study is conducted in the primary health care centers of the four health care sectors in Holy Karbala. Non probability sample (purposive sample) from the total population who meet the criteria of the study during the study interval. A total of (60) nurses selected for the study, (30) participant for study group and (30) for control group. The mean age of study group was 33.5 ± 8.1 years and that of control was 32.8 ± 8.8 years, while males were dominant in study group and controls represented 63.3% and 70%, respectively. Vast majority of the participants, 90%, in the study group and 80% of controls were married. In regard educational achievement (66.7%) and (76.7%) of (study group and control) had achieved nursing institute level of education. Comparison of mean knowledge score of study group and controls for all domains revealed no significant difference in mean scores before education program pre-test between both groups, (P>0.05), a highly significant differences in means score at post-test (1) and post-test (2), at (P<0.001). Within each group, it had been found that the change in overall knowledge scores increased significantly in the study group where the overall mean score for all domains increased from 2.36 ± 0.19 before education sessions to 2.90 ± 0.09 at post-test (1) and almost maintained to 2.87 at post-test (2), with a mean difference of 0.51 and a percentage change of 21.8%, the change was highly significant, (P<0.001). Significant improvement appear clearly among the study group member through the result of their pre-test and post-test, which explain the impact of the educational sessions content on the nurses knowledge.