Objectives: We sought to investigate the prevalence and clinical outcome of congenital left ventricular aneurysms (LVAs) and diverticula (LVD) in a large adult population. Methods: We retrospectively studied the left ventricular angiograms of 12,271 consecutive patients undergoing cardiac catheterization at our institution and analyzed the medical records of the patients. Results: The overall prevalence of LVA/LVD was 0.76% (94 patients): there were 42 patients with LVA (0.34%) and 52 patients with LVD (0.42%). Men were more likely to have LVA (62 vs. 38%), and women were more likely to have LVD (75 vs. 25%; p = 0.001 for both). The mean time of follow-up was 56 ± 6 months and was focused on clinical events, rehospitalization and survival. Mortality was 6% with no cardiac death. Patients with LVD were significantly more likely to have embolic events (p = 0.04). Patients with LVA and LVD were more likely to have rhythm disturbances compared with controls (p = 0.01 for both). Incidence of syncope was not different in both groups (p = 0.4 and 0.12, respectively). There was no reported incidence of rupture. Conclusion: This large single-center study suggests that the prevalence of LVA/LVD in adults is up to 20-fold higher than previously reported. One third of the affected patients in our series had nonfatal cardiovascular events during follow-up, with a predominance of embolic events in the LVD group.