This document discusses different econometric models for estimating the optimal hedge ratio when hedging foreign exchange risk, and whether the model specification matters. It argues that the optimal hedge ratio and hedging effectiveness are more dependent on the correlation between the unhedged position and hedging instrument, rather than the model used. Four models - levels, first difference, non-linear, and error correction model - are used to estimate hedge ratios for hedging Swiss franc, British pound, and Hong Kong dollar exposures with money markets and cross currencies from 2001-2009. Empirical evidence shows that when correlation is strong with money markets, all four models exhibit similar hedge ratios and nearly 99% hedging effectiveness. However, with