  We describe the centroid of some Leavitt path algebras. More precisely, we
show that for Leavitt path algebras over a field $K$ that are simple its
centroid is isomorphic to $K$, and for prime Leavitt path algebras its centroid
is isomorphic to $K$ except if the graph is a row-finite comet, in which case
the centroid is isomorphic to $K[x,x^{-1}]$.
