Background: A supply–demand mismatch with respect to cardiac catheterization (CATH) often results in patients experiencing waiting times that vary from a few weeks to several months. Long delays can impose both physical and psychological distress for patients. Purpose: The purpose of this study was to examine the effect of a psychoeducational nursing intervention at the beginning of the waiting period on patient anxiety during the waiting time for elective CATH. Methods: This was a 2-group randomized controlled trial. Intervention patients received a nurse-delivered, detailed information/education session within 2 weeks of being placed on the waiting list for elective CATH. Control group patients received usual care. Results: The mean waiting time for CATH was 13.4±7.2 weeks, which did not differ between groups ( P=0.509). Anxiety increased in both groups over the waiting time ( P=0.028). Health-related quality of life deteriorated over the waiting time in both groups ( P<0.05). On a visual analogue scale, there was a significant difference ( P=0.002) between the intervention (4.0±2.7) and control (5.2±3.0) groups in self-reported anxiety 2 weeks prior to CATH. Conclusions: The waiting period prior to elective CATH has a negative impact on patients’ perceived anxiety and quality of life and a simple intervention, provided at the beginning of the waiting period, may positively affect the experience of waiting.