  We prove that a strongly connected balanced bipartite directed graph of order
$2a\geq 6$ with partite sets $X$ and $Y$ contains cycles of every length $2, 4,
\ldots , 2a$, provided $d(x)+d(y)\geq 3a$ for every pair of vertices $x$, $y$
either both in $X$ or both in $Y$.
