Spontaneous splenic rupture (SSR) is a relatively rare, but potentially lethal complication of infectious mononucleosis (IM). While SSR is extremely rare in patients with proven IM, it is the most lethal complication of the infection (9% mortality rate) and can present completely asymptomatically or with abdominal pain and hemodynamic instability. As adolescents and young adults are the most affected population group, with this case report we intend to raise the vigilance of any doctor treating those patients in the emergency department. We present the case of a 16-year-old patient with an atraumatic splenic rupture and hemoperitoneum secondary to an Epstein-Barr virus (EBV) infection. The patient underwent an exploratory laparotomy, and a splenectomy was performed. This case demonstrates that even if the SSR in patients with IM is extremely rare, it should be always considered in a patient with relevant clinical presentation.