Actinomycosis is a rare chronic granulomatous infection caused by Gram-positive, non-acid-fast, anaerobic to microaerophilic bacteria.We report a case of cervicofacial actinomycosis in an 86-year-old woman undergoing immunosuppressive therapy with azathioprine and prednisone for rheumatoid arthritis. She underwent a dental treatment several months earlier. The diagnosis of culture-negative actinomycosis was based on histolopathology findings and the isolation of companion bacteria. The patient was treated with amoxicillin-clavulanic acid for 3 months, which produced complete clearance of her cervicofacial actinomycosis.Our case points out the pitfalls of diagnostic procedures in actinomycosis and the ability of this rare disease to mimic other medical conditions.