AbstractPurpose(1) to verify to what extent the occurrence of possible errors is influenced by the relationship (opaque/transparent) between fricative phonemes and the graphemes with which they can be spelled; (2) verify the differences (if present or not) of relationship types among the phonemes that present common graphemic relationships.MethodsWe analyzed 750 textual productions from children in the first year of Elementary School (ES), and conducted a survey of the frequency of correct answers and errors in all fricative phonemes of Brazilian Portuguese (BP).ResultsThe errors occurred in greater numbers in the group of phonemes with opaque spelling when compared with the number of errors in the group of phonemes with transparent spelling. In the first group, the errors showed a non-symmetrical behavior, since they varied according to the possibilities of graphemes for each phoneme. In the second group, the errors showed a symmetrical behavior.ConclusionGiven the symmetry in the errors of the phonemes of the first group and the non-symmetry of those of the second group, our results point to a gradation in the occurrence of errors, which varies as a function of the transparency and degree of opacity in the relations between phonemes and graphemes of a same class.