We present a case of tricuspid valve endocarditis in a 40-y-old woman with a history of heroin abuse. Blood cultures yielded a Gram-positive rod, preliminarily identified as "Actinomyces turicensis-like", but subsequently formally described as Actinomyces funkei sp. nov. The patient was cured by prolonged treatment with 10 weeks of i.v. antibiotics followed by oral antibiotic treatment for 12 weeks.