Benign Macrocrania of Infancy (BMI) is a clinical entity of relative frequency in the first years of life. While usually self-limited, it may lead to clinical complications that go beyond an increased head circumference, such as a higher incidence of sudural hematomas resulting from incidental, low-energy head trauma. General practictioners and surgeons must have a deep knowledge of the condition so as to prevent misdiagnoses-like non-accidental hemorrhages-and unnecessary surgical interventions. This is a case report of a twin 18-month-old boy born via cesarian section at 31 weeks gestation, being followed-up on for an increased head circumference. The magnetic ressonance imaging (MRI) study detected left parafalcine parietal subdural hematoma at the high cerebral convexity. There were no other clinical signs of non-accidental hematoma. Five months later, follow-up imaging tests identified the complete resolution of the initial hematoma and the appearance of a contralateral parafalcine subdural hematoma. Both tests showed craniofacial disproportion with dominance of the skull over the face, associated with prominent frontotemporal CSF spaces (compatible with Benign Macrocrania of Infancy). BMI is a self-limited clinical condition and that may cause repetitive subdural hemorrhage after low-energy traumas. It is, therefore, crucial to recognize this entity so as to avoid diagnostic confusion, especially with regards to nonaccidental traumas (Shaken Baby Syndrome).