Coronary artery spasm is reported to occur in 1 5% of percutaneous coronary interventions. However, coronary spasm induced solely by guidewire insertion is very rare. We present a case of diffuse coronary artery spasm induced by guidewire insertion, which responded promptly to intracoronary nitrates. The case illustrates the importance of the recognition of this phenomenon for the selection of the optimal balloon and stent size.