  Let M be a closed Riemannian manifold. We consider the inner radius of a
nodal domain for a large eigenvalue \lambda. We give upper and lower bounds on
the inner radius of the type C/\lambda^k. Our proof is based on a local
behavior of eigenfunctions discovered by Donnelly and Fefferman, and a
Poincar\'e type inequality proved by Maz'ya. Sharp lower bounds are known only
in dimension two. We give an account of this case too.
