Background and Aim:The aim of the present study was to examine nitrite concentration responses following eccentric resistance exercise (ERE) in elderly obese women. We also investigated the existence of high (HR) and low responders (LR) for nitrite and the possible differences with respect to creatine kinase (CK) response, metabolic and body composition variables. Methods: Forty-nine elderly obese women completed an ERE session utilizing knee extensor exercise. LR for serum nitrite were defined as a ∆nitrite ≤ 20th percentile or 24.1 µmol/L and HR as a ∆nitrite > 20th percentile. Results: Ten subjects were classified as LR and the remaining as HR (n = 39). The HR group displayed greater nitrite concentration at 0 h, 3 h, 24 h and 48 h following the ERE as compared with the LR (p < 0.05), and CK increased after 24 h and 48 h only for the HR group following the ERE (p < 0.05). Peak nitrite concentration was higher in the HR group versus the LR group (p < 0.05), while there was no difference between groups for pre-exercise nitrite values. The LR group displayed higher (p < 0.05) body fat, cholesterol, LDL and lower upper limb fat-free mass as compared with the HR group. The LR had lower (p < 0.05) upper limb fat-free mass than the HR group. Conclusions: Elderly obese women classified as HR displayed higher nitrite responses to ERE. Thus, researchers should be aware of the presence of different responsiveness of nitrite to acute exercise to avoid misinterpretation of data and to identify the higher cardiovascular risk factor of those classified as LR. Relevance for patients: The elevated NO up to 48 h following an ERE session may suggest an important protective cardiovascular effect. The higher body fat, cholesterol, LDL and lower upper limb fat-free mass in the LR group might represent a deleterious effect of lower serum levels of nitrite. Keywords:aging exercise nitric oxide synthase nitrite obesity responders