Over 200 bilateral and regional trade agreements are currently in force, yet their impact remains a topic of debate. We analyse effects of 27 agreements that are of particular importance for Australia on the value of merchandise trade flows using data from 1970 up to the global financial crisis in 2008. We show that preferential trade agreements generally increase trade between members but that there are often offsetting negative effects on trade with non-signatories. In contrast to regional trading blocs and bilateral accords, agreements more oriented towards open trade principles have a positive impact on all trade flows of member nations.