Fitting for connecting pipes (T), in particular at least one flexible pipe, comprising: - at least one first tubular element provided, at one end thereof, with a first inlet/outlet opening and at its interior defining a first duct ; - at least one second tubular element provided, at one end thereof, with a second inlet/outlet opening and at its interior defining a second duct , said first and second tubular elements being connected to each other at respective opposite ends to the respective inlet/outlet opening, in a manner such that said first and second ducts are in communication with each other and overall define a joint duct of the fitting placing said first inlet/outlet opening and said second inlet/outlet opening in fluid communication, wherein at least said first tubular element is provided with at least one through opening , between an external surface of the first tubular element and an internal surface of the first tubular element, said internal surface being directed towards, and defining, said first duct , said through opening defining a respective empty space between the external surface and the internal surface of the first tubular element , the fitting being configured for operating at least in an insertion condition, in which it allows a pipe (T) to be fit around said first tubular element , and a clamping condition, in which the pipe is pressed and stably locked on the first tubular element , said fitting being characterized in that , in said clamping condition, said empty space defined by said at least one through opening is configured for being at least partially occupied by a portion of said pipe (T) pressed on the first tubular element . - at least one first tubular element provided, at one end thereof, with a first inlet/outlet opening and at its interior defining a first duct ; - at least one second tubular element provided, at one end thereof, with a second inlet/outlet opening and at its interior defining a second duct , said first and second tubular elements being connected to each other at respective opposite ends to the respective inlet/outlet opening, in a manner such that said first and second ducts are in communication with each other and overall define a joint duct of the fitting placing said first inlet/outlet opening and said second inlet/outlet opening in fluid communication, wherein at least said first tubular element is provided with at least one through opening , between an external surface of the first tubular element and an internal surface of the first tubular element, said internal surface being directed towards, and defining, said first duct , said through opening defining a respective empty space between the external surface and the internal surface of the first tubular element , the fitting being configured for operating at least in an insertion condition, in which it allows a pipe (T) to be fit around said first tubular element , and a clamping condition, in which the pipe is pressed and stably locked on the first tubular element , said fitting being characterized in that , in said clamping condition, said empty space defined by said at least one through opening is configured for being at least partially occupied by a portion of said pipe (T) pressed on the first tubular element . <EOS>