A septic arthritis due to an indolent infection is a challenge for timely diagnosis. In recent years septic arthritides due to Staphylococcus Warneri are increasingly reported, mostly as a complication in patients with prosthetic devices. We report on a case of a 38 year old immunocompetent male with an indolent infection with this commensal of the skin after a stay at an intensive care unit and review the available literature. Tissue cultures obtained by arthroscopy might be helpful in obtaining a correct diagnosis.