Rothia mucilaginosa is an opportunistic agent detected in the upper respiratory tract and oral cavity in humans. Immunocompromised hosts have more risk to develop severe infections. We present a short review and two clinical cases of Rothia mucilaginosa bloodstream infection in children with leukemia, one of them with endocarditis. Both were completely recovered. Predisposing factors for Rothia mucilaginosa infection include profound and prolonged neutropenia, use of central venous catheter, mucositis and high dose steroid. It is important to consider this bacterium as an emerging causative agent of severe infection in immunocompromised patients, especially in the presence of the mentioned factors.