  Searches for tetraquarks and mesonic molecules in lattice QCD are briefly
reviewed. In the light quark sector the most serious candidates are the
lightest scalar resonances sigma, kappa, a0 and f0. In the hidden-charm sector
I discuss lattice simulations of X(3872), Y(4260), Y(4140) and Z^+(4430). The
most serious challenge in all these lattice studies is the presence of
scattering states in addition to possible tetraquark/molecular states. The
available methods for distinguishing both are reviewed and the main conclusions
of the simulations are presented.
