We present an improvement of pattern matching algorithm for arc-annotated sequences. Arc-annotated sequences are used for representing the structural information,
, RNA and protein sequences in molecular biology. Given two sequences with arcs, a text of length
and a pattern of length
, the problem is to determine whether the pattern is an arc-preserving subsequence of the text. Although it is NP-complete in a general case, an
) algorithm has been proposed if the given sequences have no crossing-arcs. Our contribution is to revise it and to obtain more simple one. We also present our experimental results of the running time.