BackgroundDelirium is a common but often underdiagnosed set of transient symptomin the elderly patients following surgeries under spinal anesthesia. Delirium can be improved with early recognition and diagnosis based on the established standard criteria. The identification of the possible contributing factors and magnitude of the burden will help in the management of the fragile elderly patients. Managing delirium with environmental, supportive and pharmacological interventions will possibly reduce the incidence, and complication associated with postoperative delirium. The aim of this study is to determine the incidence of postoperative delirium and associated risk factors in elderly patients who did surgery under spinal anesthesia. MethodThis cross sectional study was conducted in the National Referral Hospitals in Eritrea (Orotta and Halibet), including Sembel hospital from February to May, 2019. The study participants were elderly patients (age ≥65 years) having no mental disorder, no history of acute cerebrovascular disease, no known history of delirium and/or dementia. Basic background and clinical characteristics of the patients was collected. To assess the status of cognitive impairment level, the Mini Mental State Examination and Confusion Assessment Method tools were used. Data was collected through an interview method. After the data was entered into SPSS version 22 software, it was conducted with frequency, percentage, bivariate and multivariate logistic regression analysis method as appropriate. P value at<0.05 was considered as statistically significant. ConclusionPostoperative delirium occurred in 14 out of 129 case (10.9%). The multivariate analysis showed that only age was significantly associated with postoperative delirium. The other variables did not significantly influence the occurrence of POD. Therefore, t he incidence of postoperative delirium after spinal anesthesia was relatively high (10.9%). Similarly, old age was found as the risk factor for the development of delirium in those elderly patients who underwent spinal anesthesia. This findings might help to develop preventive strategies to decrease POD through targeted factors.