This paper proposes a straightforward model for analysing the impact of export commodity price fluctuations on open macroeconomies with particular reference to Australia and New Zealand, major commodity exporters in the Asian region. It extends the dependent economy approach, first by re-specifying goods and services production as either exportable, importable or non-tradable, and second by adding a monetary sector to highlight key linkages between commodity prices, the exchange rate, price level, national output and trade account. The framework sheds new light on the phenomenon of 'commodity currencies', how exchange rate movements shield national output from terms of trade shocks, the importance of economic openness in this process, and the significance for monetary and exchange rate policy of short term, versus sustained, commodity price movements. (C) 2012 Elsevier Inc. All rights reserved.