<p><it>Abstract—</it>We give an optimal algorithm that broadcasts on an $<tmath>n</tmath>$-dimensional hypercube in $<tmath>\Theta(n/\log_2(n+1))</tmath>$ routing steps with wormhole, $<tmath>e</tmath>$-cube routing and all-port communication. Previously, the best algorithm of McKinley and Trefftz requires $<tmath>\lceil{n/2} \rceil</tmath>$ routing steps. We also give routing algorithms that achieve tight time bounds for $<tmath>n \le 7</tmath>$.</p>