Sport footwear, such as a ski boot, or similar sport footwear, comprising at least a rigid shell which has a front aperture, a front toe-box and a front end portion comprised between said front aperture and said toe-box along a longitudinal axis of development of the shell, comprising: - a weakening notch with an elongated shape and made through in said front end portion of said shell and configured to allow a volumetric variation of the shell at least in correspondence to said front end portion; - tie-rod means (30a, 130a, 230a) associated at the upper part to said weakening notch, to define the desired volumetric variation, said tie-rod means being configured to act in traction in a direction transverse to said longitudinal median axis and comprising at least a front terminal closing mechanism (30a, 130a, 230a) provided in said front end portion overlapping said weakening notch, said front terminal closing mechanism (30a, 130a, 230a) being attached to lateral portions (25a, 25b) of the shell which laterally delimit the front aperture and being configured to assume at least an unclamped condition and a clamped condition in which said lateral portions (25a, 25b) are brought near each other, characterized in that said weakening notch is inclined and in a non-symmetrical position, at the side with respect to said longitudinal median axis and the sport footwear further comprises: - a rigid or semi-rigid covering member attached to said front end portion of the shell and provided with a first lower end segment configured to irremovably cover said front end portion, and with a second upper segment, hinged to said first lower segment and configured to selectively assume a closed condition, to cover said front aperture, and an open condition in which it is rotated toward said front end portion with respect to the front aperture; and - a protection element interposed between the second upper segment of the covering member and the front aperture of the shell and configured to protect said front aperture when the second upper segment is in said open position. - a weakening notch with an elongated shape and made through in said front end portion of said shell and configured to allow a volumetric variation of the shell at least in correspondence to said front end portion; - tie-rod means (30a, 130a, 230a) associated at the upper part to said weakening notch, to define the desired volumetric variation, said tie-rod means being configured to act in traction in a direction transverse to said longitudinal median axis and comprising at least a front terminal closing mechanism (30a, 130a, 230a) provided in said front end portion overlapping said weakening notch, said front terminal closing mechanism (30a, 130a, 230a) being attached to lateral portions (25a, 25b) of the shell which laterally delimit the front aperture and being configured to assume at least an unclamped condition and a clamped condition in which said lateral portions (25a, 25b) are brought near each other, - a rigid or semi-rigid covering member attached to said front end portion of the shell and provided with a first lower end segment configured to irremovably cover said front end portion, and with a second upper segment, hinged to said first lower segment and configured to selectively assume a closed condition, to cover said front aperture, and an open condition in which it is rotated toward said front end portion with respect to the front aperture; and - a protection element interposed between the second upper segment of the covering member and the front aperture of the shell and configured to protect said front aperture when the second upper segment is in said open position.