Rapid engagement/release coupling, comprising: - a female connector having a hole with an insertion end, a cylindrical sealing portion and an annular groove located between the insertion end and the cylindrical sealing portion, the annular groove having a first stop surface, - a male connector carrying a sealing ring configured to cooperate with said cylindrical sealing portion of the female connector and having a recessed annular portion having a second stop surface, - a retaining ring having a collar and a tubular portion equipped with a plurality of longitudinal splits that divide the tubular portion into a plurality of elastically deformable sectors, said sectors having respective teeth configured to engage the annular groove of the female connector, wherein said teeth have respective outer surfaces configured to engage said first stop surface, and respective inner surfaces configured to engage said second stop surface, wherein the retaining ring is inserted on a cylindrical portion of the male connector, such that the male connector with the retaining ring mounted on it can be inserted into or removed from the hole of the female connector, wherein the male connector is axially movable with respect to the retaining ring between a working position and a disengaged position, wherein in said working position said second stop surface of the male connector is in contact with said inner surfaces of said teeth and prevents an inwardly radial deformation of the elastically deformable sectors, wherein in said disengagement position, said recessed annular portion of the male connector is disengaged from said teeth and forms an empty space level with said elastically deformable sectors, wherein in said disengagement position said elastically deformable sectors are free to deform radially inwards, wherein in said disengagement position the male connector with the retaining ring mounted on it can be inserted into the hole of the female connector, and during the axial movement of the retaining ring with respect to the female connector said teeth are free to engage or disengage said annular groove of the female connector, characterized in that said inner and outer surfaces (66, 68) of said teeth are conical surfaces having different inclination angles (α1, α2) with respect to a longitudinal axis, the inclination angle (α1) of said outer conical surfaces being greater than the inclination angle (α2) of said inner conical surfaces. - a female connector having a hole with an insertion end, a cylindrical sealing portion and an annular groove located between the insertion end and the cylindrical sealing portion, the annular groove having a first stop surface, - a male connector carrying a sealing ring configured to cooperate with said cylindrical sealing portion of the female connector and having a recessed annular portion having a second stop surface, - a retaining ring having a collar and a tubular portion equipped with a plurality of longitudinal splits that divide the tubular portion into a plurality of elastically deformable sectors, said sectors having respective teeth configured to engage the annular groove of the female connector, wherein said teeth have respective outer surfaces configured to engage said first stop surface, and respective inner surfaces configured to engage said second stop surface,