Veillonellasp. andV. disparare emerging pathogens. This is the third case of a monomicrobialVeillonellasp. prosthetic joint infection (PJI) among knees and hips; this is the second prosthetic knee infection described. The infection was treated with a 2-stage procedural approach combined with 6 weeks of ceftriaxone with excellent clinical response. There was no relapse in 2 years of follow-up care. This case exemplifies the importance of incubating anaerobic cultures for at least 7 days to grow some anaerobic pathogens.