The present invention relates to a method for equalizing modulation symbols transmitted on a non-linear transmission channel. The equalizing method operates on a sequence of observables, each non-linearly depending on a predetermined number of consecutive modulation symbols, and is based on a Viterbi algorithm. It comprises a prior step of receiving a pilot sequence of modulation symbols and storing corresponding observables (110), said pilot sequence leading to a path passing through all the branches of the lattice.In a second step (120), for each symbol to be equalized, for each branch, a branch metric is calculated as a distance between the observable corresponding to the modulation symbol to be equalized and the observable stored for said branch.