Splenic infarction is rare, resulting from occlusion of the splenic artery or its branches. Its aetiology is complex and multifactorial involving various vascular and thrombotic diseases, thus, misdiagnosis or missed diagnosis is common. Here, the case of a 45-year old male patient diagnosed with splenic infarction caused by secondary erythrocytosis associated with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is reported. The patient presented with 10 days of abdominal distension and pain that worsened after eating, and had developed to include nausea, vomiting and fever. The patient had a history of night snoring for over 10 years without treatment, a diagnosis of chronic pulmonary heart disease and secondary polycythaemia 5 years previously, and diagnosis of OSAHS 1 year previously. He had not received previous non-invasive ventilation or oxygen therapy. Enhanced upper abdomen computed tomography (CT) showed splenic infarction, bone marrow cytology suggested secondary polycythaemia, and sleep polysomnography revealed severe OSAHS. Low molecular-weight heparin, ceftriaxone, fluid and oxygen treatment gradually relieved abdominal distension and pain. Enhanced CT showed splenic infarction improvement. The present case highlights that splenic embolism should not be ignored as a potential complication of OSAHS.