A 27-year-old white male, who had sex with other men, presented to the emergency department with 3 days of left shoulder and abdominal pain. He reported no history of trauma to the abdomen. On abdominal imaging, he was found to have hemoperitoneum from a ruptured spleen; he underwent splenectomy. Causes of atraumatic splenic rupture can be divided into six main categories: infectious, neoplastic, inflammatory, congenital or structural, iatrogenic, and idiopathic. Work-up of the atraumatic splenic rupture revealed that his HIV antibody was newly positive. He had a documented negative HIV antibody 3 weeks prior to the current admission. CD4 cell count, obtained after splenectomy, was 904 cells per microliter and the HIV-1 plasma RNA level was 4657 copies per milliliter. Spleen pathology demonstrated an enlarged spleen with increase in the number of small to intermediate size lymphoid cells in the red pulp, and reactive follicular lymphoid hyperplasia, with numerous secondary lymphoid follicles and reactive germinal centers in the white pulp. T-cell receptor (TCR) gene rearrangement studies demonstrated a positive TCR beta gene rearrangement, without a TCR gamma gene rearrangement, consistent with a clonal CD8(+) T-cell population. The case gives rare insight into what happens in the spleen during acute HIV infection and encourages HIV testing in those presenting with atraumatic splenic rupture. Counseling patients with acute HIV to avoid potential trauma should also be considered.