Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired X-linked, clonal hematopoietic stem cell disease. Patients with PNH may complain of vague symptomatology that contributes to the challenge of its diagnosis. This is especially true in the clinical context of a coinciding hematologic disorder. Aplastic anemia (AA) is an additional immune-mediated illness that results in the destruction of hematopoietic precursors and pancytopenia. The authors encourage screening for PNH clones in patients initially diagnosed with AA, treating underlying hematologic disease to prevent clonal expansion, and further research to investigate the effectiveness of eculizumab in an unusual "classical" PNH secondary to AA with hypercellular bone marrow.