Background & aims: The significance of abdominal wall thickness (AWT) for nutritional assessment remains unclear. This study aimed to evaluate the nutritional and prognostic significance of AWT measured during percutaneous endoscopic gastrostomy (PEG) in older patients with dysphagia. Methods: This single-center retrospective cohort study enrolled older adults with dysphagia who underwent PEG for enteral nutrition using the introducer technique between February 2010 and January 2019. We examined the association between AWT measured during PEG and nutritional status items, including body mass index (BMI), serum albumin (Alb), total lymphocyte count (TLC), total cholesterol (TC), hemoglobin (Hb), and C-reactive protein (CRP). The shaft length of the PEG tube inserted, which is an approximation value of the AWT, was used for statistical analysis. Patients were divided into three groups: low-AWT group (shaft length 2.5 cm), medium-AWT group (shaft length 3.0e3.5 cm), and high-AWT group (shaft length !4.0 cm). We performed the KruskaleWallis test and multiple linear regression analysis with multiple imputation. We performed survival analysis using the KaplaneMeier method, log-rank test, and Cox regression analysis. Results: A total of 520 patients were identified: 115, 258, and 147 patients in the low-AWT, medium-AWT, and high-AWT groups, respectively. Higher AWT was significantly associated with higher BMI, Alb, TLC, TC, Hb, and lower CRP levels. Multiple linear regression analysis revealed that BMI and TLC were significant predictors of AWT (BMI: coefficient 1.16E-01, 95% confidence interval [CI], 9.77E-02e1.33E-01, P < 0.001; TLC: coefficient 1.18E-04, 95% CI, 2.72E-05e2.09E-04, P ¼ 0.011). The median survival time was the longest in the high-AWT group (low-AWT, 359 days; medium-AWT, 851 days; high-AWT, 1662 days; P < 0.001). The hazard ratio for the high-AWT group relative to the medium-AWT group was 0.59 (95% CI, 0.41e0.85, P ¼ 0.004), and that relative to the low-AWT group was 0.34 (95% CI, 0.24e0.51, P < 0.001). Conclusions: Higher AWT was associated with better nutritional status and survival. AWT may help assess nutritional status and predict survival in older dysphagic patients with PEG.