Abstract: A Luer-Lock fitting comprising a tubular body having at one end an outer Luer cone connector coaxially surrounded by an innerly threaded attachment cup-like element, and a detachable cap sealingly fitted axially over the Luer cone connector. The cap is formed by a tubular member interposed between the Luer cone connector and the attachment element, which carries a transverse filtering barrier and whose inner end is forcedly coupled onto the outer surface of the Luer cone connector, in proximity of the bottom of the attachment element, so as to define along a substantial portion of the outer surface of the Luer cone connector an annular interspace, opening towards the filtering barrier.