Abstract: The problem. The purpose of the present study was to assess the prevalence and severity of Posttraumatic Stress Disorder (PTSD) in patients with heart disease and an Implantable Cardioverter Defibrillator. Method. A quasi-empirical study was conducted to determine the prevalence and severity of PTSD in heart patients with and without an ICD as well as between ICD patients who had received an ICD shock or experienced an ICD storm and a shock within the first year of having the ICD. Sixteen ICD patients and 15 heart disease patients completed a demographic questionnaire and the Posttraumatic Stress Diagnostic Scale. Data was gathered from heart patients referred by their cardiologists and from heart patients who subscribe to one of three online support forums. Results. Due to a positively skewed distribution of symptom severity scores, non-parametric procedures were utilized. Mann-Whitney U tests were calculated to assess the difference between the symptom severity scores (dependent variable) of the non-ICD and ICD (independent variable) subject population. A Bonferroni Correction was conducted to reduce the impact of multiple comparisons, which reduced the significance level from .05 to .01. A Fishers Exact Test was utilized to determine if diagnostic criteria for PTSD was met for a greater number of ICD than the non-ICD patients. There were significantly more patients who met diagnostic criteria for PTSD in the ICD population than in the non-ICD population. Mann-Whitney U tests were also calculated to determine if the PTSD symptom severity scores were greater for ICD patients who had received a shock, a storm, and received their first shock within the first year of implantation. There were no significant differences found for any of these hypotheses. An additional analysis was conducted looking at trends noticed in the research. A Spearman Rank Order Correlation was conducted to determine if there was a relationship between a person's age and his or her PTSD symptom severity scores. A significant negative relationship was found. A Fishers Exact Test determined that recruitment methods did not have a significant impact upon PTSD symptom severity scores.