A new algorithm for finding line spectral frequencies, LSF, is introduced, based on Laguerre method of root approximation. The method allows to assuredly find all roots one by one without recourse to polynomial deflation, which allows approximation to a high precision. Error bounds can be estimated by approximating from two sides with added margin. An improved variant of Laguerre recursion scheme is proposed to deal with unfavourable starting points, resulting in faster convergence.