Primary heart tumors are very rare. Reyne et al. reported a prevalence of 0.02% for heart tumors in 22 autopsies [1]. Primary heart lymphomas are even more rare, with a prevalence between heart tumors from 1 to 2% and 0.5% of all lymphomas [1,2]. We will report one case of a 69-year-old woman with a mass in the right atrium, with hemodynamic compromise, with the histological finding of a primary heart diffuse type B lymphoma.