A connector for medical lines, comprising a tubular body (1) having a male luer-lock fitting (2) at one end, intended to be screw-coupled with a complementary female fitting. An outer jacket (5) is coupled in unidirectional rotation with the tubular body (1) in the direction corresponding to the screwing of the male fitting (2) and freely rotatable in the opposite direction. For selectively coupling the outer jacket (5) with the tubular body (1) in the direction corresponding to the unscrewing of the male fitting (2) at least one side push-button (8) carried by said outer jacket (5) is provided.
