Image-based measurement of sarcopenia is an established predictor of a decreased outcome for a large variety of surgical procedures. Sarcopenia in elderly patients undergoing emergency abdominal surgery has not been well studied. This study aims to investigate the association between the total psoas area (TPA) and postoperative mortality after 90 days in a group of elderly emergency laparotomy patients. We retrospectively reviewed the emergency CT-scans of 150 elderly patients from a consecutive cohort undergoing emergency abdominal surgery at our surgical center. TPA was measured manually at the level of L3 and indexed to patient height. Sarcopenia was defined as having a TPA index below the first quartile for gender in the cohort. Other collected variables were age, vital status/date of death, ASA-score, surgical procedure, and WHO performance score. Overall 90-day mortality was 42.7%. Sarcopenic patients had a higher 90-day mortality (60.5%) than non-sarcopenic patients (36.6%), corresponding to an odds ratio of 2.66 (95% confidence interval 1.2-5.7, p = 0.01). Sarcopenic patients had an increased mortality compared with non-sarcopenic patients (p = 0.0009, Log-rank test), with a clear separation of the two groups within 30 days postoperatively. In a multivariate logistic regression model, with age, ASA-score, and WHO performance score as covariates, sarcopenia was independently associated with 90-day mortality. Manual measurement of TPA on an abdominal CT-scan is a relevant risk factor for postoperative mortality in elderly patients undergoing high-risk emergency abdominal surgery. Incorporation of sarcopenia in postoperative risk-prediction models in emergency abdominal surgery should be considered.