Technology helps to assess the daily living of frail people and may have a strategic role to detect and prevent falls. In this paper, the task of classifying different classes of postural sway behaviors has been addressed by developing a Neuro-Fuzzy inference approach that is robust against noise. The proposed approach classifies four different postural behaviors namely Stable Standing, Antero-Posterior, Medio-Lateral and Unstable. The strategy exploits data generated by a wearable sensor node, to be positioned on the user chest. A dedicated experimental set-up has been realized to emulate the postural dynamics and generate the dataset. Two novel indices to assess the robustness of the system have been proposed. The first index is a measure of residuals between the predicted and the expected postural status, which equally weights estimations with respect to expected classes. The second metric is a reliability index, which allows for assessing the degree of trust of each estimation performed by the Neuro-Fuzzy inference. Results obtained demonstrate the suitability of the proposed methodology, showing a capability of almost 100% to correctly classify patterns among different allowed classes, with reliability indexes of 97.56% and 98.50% for the training and test patterns, respectively. Also, robustness of the Neuro-Fuzzy classification algorithm against noisy data has been demonstrated.