We report a case of a radial artery pseudoaneurysm complicating a single arterial puncture for blood-gas analysis that was treated with excision of pseudoaneurysm and suture of the defect of wall of radial artery. The puncture for continuous blood pressure monitoring and serial blood gas analysis have been reported in critically ill patients, but, to the best of our knowledge, there are no cases reported of pseudoaneurysm after a single arterial puncture for blood-gas analysis. In the reported case we think that the main cause of the pseudoaneurysm onset was an incorrect compression and/or a too much short time of compression of the radial artery after the puncture. Minor sequelae and rare complications may be minimized by careful attention to detail in the performance of such procedures and care of the patient also after a single arterial puncture.