Abstract: Objective: To investigate the risk factors for chemotherapy related toxicities (CRT) and construct a nomogram for CRT risk estimation in patients aged over 70 years with advanced gastric cancer. Methods: Patients aged over 70 years with advanced gastric cancer who were admitted to Peking Union Medical College Hospital from July 2003 to August 2020 were enrolled in this retrospective study. Clinicopathological data of these patients were obtained. Logistic regression analyses were performed to investigate the relationship between variables and CRT. A nomogram for CRT was constructed and verified using bootstrap resampling. The calibration curve was applied to demonstrate the conformity between the model curve and ideal curve. Results: Among the 178 patients, the incidence of CRT was 41%. Female, ECOG ≥1, weight loss, prechemotherapy blood albumin <30g/L, prechemotherapy neutrophil and lymphocyte ratio (NLR) <4, and prechemotherapy platelet count were independent risk factors for CRT. A nomogram of CRT was developed based on these six risk factors. The nomogram showed good diagnostic performance area under the curve (AUC)=0.716, 95% confidence interval (CI)=0.677–0.755. This nomogram presented good fitting in the calibration curve. Conclusions: We constructed a nomogram for predicting CRT risk in patients with advanced gastric cancer aged over 70 years. This nomogram may be applied as a non-invasive and convenient model to detect early warning signs of CRT in these patients.