The major objective of this paper is to determine what impact energy prices have had on input substitution. If a micro approach is taken, it is felt that the actual reaction of output cannot be determined, as many macroeconomic forces also affect output in the economy. Determining the relationship of inputs, or the response of inputs, to increased energy prices is the first step in determining the effect higher energy prices have on the economy. Two models which estimate the relationship of inputs in the production process are presented in this paper using data for 20 manufacturing sectors and agriculture for 1947 to 1976.