  In this paper, we study Randers metrics and find a condition on Ricci tensor
of these metrics to be Berwaldian. This generalize Shen's Theorem which says:
every R-{\deg}at complete Randers metric is locally Minkowskian. Then we find a
necessary and sufficient condition on Ricci tensor under which a Randers metric
of scalar {\deg}ag curvature is of zero {\deg}ag curvature.
