We report a rare case of native tricuspid valve infective endocarditis caused by Neisseria mucosa/sicca, a gram-negative diplococcus which colonizes the upper respiratory tract. A female in her late 20 s with a history of injection drug use (IDU) who recently completed treatment for methicillin-sensitive Staphylococcus aureus (MSSA) native tricuspid valve infective endocarditis presented to the hospital with a 6-week history of increasing chest pain, shortness of breath and night sweats. Blood cultures grew Neisseria mucosa/sicca species in 3 of 3 sets. Transthoracic echocardiogram showed a large 3 cm × 2.2 cm vegetation on the tricuspid valve with severe regurgitation. The patient was initially treated with ceftriaxone and gentamicin. Her case was complicated by ongoing septic pulmonary emboli ultimately require pulmonary endarterectomy and repair of her tricuspid valve. We hope this case highlights a rare but known cause of infective endocarditis especially in patients with a history of IDU who may lick their needles, which predisposes those individuals to intravenous introduction of oral bacteria.