Introduction: Splenic infarction is the consequence of splenic parenchymal ischaemia related to occlusion of the splenic artery or one of its branches. We report a case of splenic infarction associated with a complex congenital heart disease discovered in adulthood. Clinical observation: A 49-year-old sedentary female patient was admitted with progressive moderate pain in the left hypochondrium and dyspnoea. Clinical examination revealed auscultatory arrhythmia, exquisite left hypochondral pain and congestive heart failure syndrome. The electrocardiogram showed atrial fibrillation, while the echocardiogram showed an atrioventricular canal and a single right ventricle. The chest X-ray showed cardiomegaly with significant protrusion of the pulmonary artery. Abdominal angioscan was consistent with splenic infarction, while the laboratory work-up was normal. Complex congenital heart disease associating an atrioventricular canal and a single ventricle decompensated into congestive heart failure complicated by atrial fibrillation with splenic infarction was the diagnosis adopted. The patient was treated with furosemide, enalapril, spironolactone and enoxaparin. The patient died on the third day of hospitalization. Conclusion: This observation shows that in the absence of early diagnosis and appropriate treatment, complex congenital heart disease can lead to major complications, particularly thromboembolic.