This study identifies and provides an estimate of the impact of bank liquidity shocks on real economic activity by exploring letter‐of‐credit import transactions in Colombia during the 2008 to 2009 global financial crisis. The detailed dataset on letter‐of‐credit transactions allows for exploiting within‐importer–exporter variation across issuing banks. The study finds substantial effects of bank liquidity shocks on letter‐of‐credit import transactions: banks that were more vulnerable to adverse liquidity shocks—proxied by the ex ante reliance on wholesale funding or borrowings from foreign banks—reduced letter‐of‐credit issuances more in both intensive and extensive margins. The study also confirms that it had real effects: importer–exporter pairs that relied more on letter‐of‐credit transactions experienced a greater reduction in their total imports in response to adverse bank liquidity shocks.