A method and apparatus for decoding code words which are error protected by a non-binary BCH-code against at least one symbol error. Upon reception of an input code word a syndrome information thereof is generated under control of code defining information. From the syndrome information, a key equation is set up and solved for generating an error locator polynomial sig (z) and an error evaluator polynomial w(z). On the basis of the polynomial sig (z) and its formal derivative polynomial sig' (z), Euclid's algorithm is employed to calculate two accessory polynomials b(z), c(z), such that b(z)sig(z)+c(z)sig'(z)=1. From these, a Lagrangian polynomial L(z) is calculated which for any inversed error location value has the associated error symbol value. The error data is then calculated by evaluating the error locator polynomial and the Lagrangian polynomial.