121 Background: 30 day readmission has become an important metric in healthcare delivery. Policymakers have started to factor in readmission rates in their recommendations on reimbursement algorithms. It is unclear whether these methods are applicable to cancer patients. More studies are needed in order to understand readmission in the context of cancer patients. A few studies have found that the elderly and those with gastrointestinal (GI) malignancies are at risk. Methods: We conducted a retrospective cohort study using linked Texas Cancer Registry and Medicare claims data to describe the patterns of 30 day unplanned readmission among GI cancer patients in Texas. Only short stays to acute care hospitals were included in the study. Claims data were analyzed for a period of 2 years from the date of cancer diagnosis. Modified Poisson regression model was used to identify factors associated with the outcome. Results: 30,199 patients aged 66 and above were included in our study. The incidence of unplanned readmission in our cohort was 15%. The top 10 reasons for readmission were fluid and electrolyte disorders, secondary malignancies, complications of surgical procedures and medical care, congestive heart failure, intestinal obstruction, pneumonia, sepsis, GI hemorrhage, urinary tract infections, and complications of device, implant or graft. After multivariate analysis, age >80 (OR 0.79, 0.73-0.85), regional (1.19, 1.11-1.27) and distant disease (1.16, 1.07-1.25), living in less affluent neighborhoods (1.10, 1.01-1.19), and increasing comorbidity index (p<0.0001) were associated with 30 day readmission. Esophageal cancer carried the highest risk for 30 day readmission (1.53, 1.38-1.70). Conclusions: Most of the top reasons for readmission appear to be cancer-related. This means that most of these readmissions are likely not preventable. This should be taken into consideration by policymakers when making recommendations. There are, however, some that may be amenable to outpatient management. This further underlines the importance of primary care involvement in the management of cancer patients. Risk factors identified can help risk–stratify patients who may need early follow up post-discharge, in order to prevent early readmission.