Noise is source of ambiguity for fuzzy systems. Although being an important aspect, the effects of noise in fuzzy modelling have been little investigated. This paper presents a set of tests using three well-known fuzzy modelling algorithms. These evaluate perturbations in the extracted rule-bases caused by noise polluting the learning data, and the corresponding deformations in each learned functional relation, We present results to show: 1) how these fuzzy modelling systems deal with noise; 2) how the established fuzzy model structure influences noise sensitivity of each algorithm; and 3) whose characteristics of the learning algorithms are relevant to noise attenuation.