Arrhythmias represent one of the most clinically significant long-term complications in adults with ventricular septal defect (VSD). According to major cohort studies, their prevalence ranges from 12% to 45% and depends on shunt duration, chamber dilation, pulmonary hypertension, and postoperative or spontaneous myocardial scarring. Atrial arrhythmias, including atrial fibrillation and flutter, are the most common types and are strongly associated with right atrial enlargement and chronic volume overload. Ventricular tachycardias occur less frequently but carry a substantially higher risk of adverse outcomes, particularly in the presence of postoperative scar or myocardial fibrosis detected by late gadolinium enhancement cardiac MRI. Conduction disturbances including right bundle branch block and varying degrees of atrioventricular block are frequently observed in perimembranous VSDs and after surgical repair. Advances in extended ECG monitoring, electrophysiological testing, and cardiac MRI have significantly improved risk stratification. Catheter ablation and implantable cardioverter-defibrillators serve as effective therapeutic options in patients with refractory or life-threatening arrhythmias. A targeted literature review was performed focusing on arrhythmias in adults with congenital heart disease, including VSD. Searches were conducted in PubMed, Scopus, Web of Science, and the Russian eLIBRARY (RINC) database. The search period covered publications from January 2000 to October 2025. Studies were included if they reported data on prevalence, mechanisms, diagnostic evaluation, or treatment of arrhythmias in patients aged ≥18 years. Exclusion criteria were pediatric-only studies without separate adult analysis, insufficient methodological detail, or lack of arrhythmia-related outcomes. A total of 20 key publications were selected for detailed synthesis.