This paper investigates whether a systematic monetary policy can affec
t output in a dynamic menu cast model that results in (S, s) price rul
es. It will be shown that monetary policy potentially can affect outpu
t, not only in the short run but also with regard to long-run average
output. Even though the policy rule is fully known by the rational fir
m, perfectly anticipated monetary policy intervention may have. perman
ent real effect in the long run.