Sur g ical site infection is a si g nificant health problem amon g nosocomial infections, leadin g to post -operative mortality in sur g ical older adults. Identifyin g risk factors is essential in sur g ical care q uality. This retrospective cohort study, conducted at a university hospital in Ban g kok, ri g orously examined the sur g ical site infection rate and its predictive factors in older adults under g oin g abdominal sur g ery. The study employed convenience samplin g to recruit 300 older adults who underwent abdominal sur g ery usin g the code of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and completion of electronic medical records between January 1 and December 31, 2020. The instruments used included the Demo g raphic Characteristics Form, the Preoperative Clinical Characteristics Form, the Intraoperative Record Form, and the Post -operative Record Form. The data collected were analyzed usin g descriptive statistics and binary lo g istic re g ression analysis, ensurin g a comprehensive and robust analysis of the risk factors for sur g ical site infection in older adults under g oin g abdominal sur g ery. The results of this study revealed that 63.25% of participants were female, with a mean a g e of 74.5 years. The sur g ical site infection rate was 12 per 100 patients, varyin g across anatomical locations and sur g ical procedures, ran g in g from 0.33% to 5.66%, with colon sur g ery bein g the most common. The study identified si g nificant risk factors predictin g sur g ical site infection, includin g comorbidities and obesity class 2, while the American Society of Anesthesiolo g ists Physical Status class 2 and 3 were identified as protective factors. These findin g s provide a powerful tool to screen patients at risk of sur g ical site infection in nursin g practice, particularly with older adults under g oin g colon sur g ery, and to prevent sur g ical site infection.