  Let $M$ be a compact hyperkaehler manifold. The hyperkaehler structure equips
$M$ with a set $R$ of complex structures parametrized by $CP^1$, called "the
set of induced complex structures". It was known previously that induced
complex structures are non-algebraic, except may be a countable set. We prove
that a countable set of induced complex structures is algebraic, and this set
is dense in $R$. A more general version of this theorem was proven by Fujiki.
