  An antimagic labeling of a graph $G$ with $m$ edges is a bijection from
$E(G)$ to $\{1,2,\ldots,m\}$ such that for all vertices $u$ and $v$, the sum of
labels on edges incident to $u$ differs from that for edges incident to $v$.
Hartsfield and Ringel conjectured that every connected graph other than the
single edge $K_2$ has an antimagic labeling. We prove this conjecture for
regular graphs of odd degree.
