We study the worst-case performance of the maximal matching heuristic applied to the Minimum Vertex Cover and Minimum Maximal Matching problems, through a careful analysis of tight examples. We show that the tight worst-case approximation ratio is asymptotic to min{2, 1/(1 − √ 1 − )} for graphs with an average degree at least n and to min{2, 1/ } for graphs with a minimum degree at least n. These bounds apply to both problems and are obtained through a careful analysis of the tight examples.