Examination of the flow of branched polyethylene melts leads to molecular weight‐viscosity, activation energy‐molecular weight, and activation energy‐shear stress relationships which are anomalous when compared to the behavior of most polymers. In addition, the activation energy for viscous flow is much higher than would be expected by a comparison with linear polyethylene. Published data on branched polyethylene are examined, and various explanations for the anomalous behavior are considered. Order in the melt and abnormal melt volumes are rejected as possible explanations for the anomalous effects. It is shown that short branches contribute at most ca. 2 kcal to the activation energy at zero shear and cannot, therefore, be completely responsible for the observed values. Long chain branches are postulated for several reasons to be responsible for the anomalous flow behavior and activation energy. The mechanism by which long chain branches cause the anomalous behavior of branched polyethylene is not established, but several possible explanation are discussed.