Rosacea is a common skin disease in adults affecting mainly the facial skin. Although inflammation appears to play a pathogenic role in rosacea, initiating factors are largely unknown. Microbial involvement in the development of rosacea has been suggested previously. We aimed to visualize Propionibacterium acnes in the skin compartments of rosacea patients. Facial skin biopsies from 82 rosacea patients and 25 controls were stained with a P. acnes-specific monoclonal antibody (QUBPa3). Seven of 82 patients (8.5%) tested positive for P. acnes which was present either as a biofilm (57% of positive) or a microcolony (43%) in colonized patients. Our results suggest that P. acnes does not play a major role in the pathogenesis of rosacea.