We investigate the set of cycle lengths occurring in bipartite graphs with large minimum degree. A bipartite graph is weakly bipancyclic if it contains cycles of every even length between the length of a shortest and a longest cycle. In this paper, it is shown that if G = (V-1, V-2, E) is a bipartite graph with minimum degree at least n/3 + 4, where n = max {[V-1], [V-2]}, then G is a weakly bipancyclic graph of girth 4. This improves a theorem of Tian and Zang (1989), which asserts that if G is a Hamilton bipartite graph on 2n(n >= 60) vertices with minimum degree greater than 2n/5 + 2, then ...
