Rationale: Spontaneous rupture of the branches of left subclavian artery (LSA) without any obvious risk factors is rare.
Patient concerns: A 51-year-old female patient without history of trauma and hypertension complained about left chest pain.
Diagnoses: A chest Computed tomography (CT) scan revealed a large pleural effusion (PE) in the left thorax cavity and hemothorax was confirmed by thoracentesis.
Interventions: The patient underwent surgery.
Outcomes: spontaneous rupture of the branches of LSAwas confirmed.
Lessons: The patient recovered well and discharged after timely treatments. The unusual possibility should be paid attention in mind in acute chest pain cases.