A protective hood suitable to be worn, in sterile form, by an operator, in particular in an operating room or in a clean room, over a helmet, which protective hood is supplied in folded form and includes: ▪ a front vision lens, apt to be positioned, in use, at least at the operator's eyes, ▪ an enveloping main body, fixed to said vision lens at a peripheral region of the latter and configured to cover completely the operator's head, neck and an upper part of the chest, which enveloping main body comprises a front portion and a rear portion connected and made integral by two opposite side portions (13, 14), characterized in that it further comprises ▪ a first and a second lateral string, each one fixed, at a respective terminal end, on said rear portion of said enveloping main body, said first and second string being arranged on opposite sides with respect to a longitudinal axis of the hood, which first and second string are configured to be grasped by the operator during wearing of the hood in order to unwind said rear portion and bring it to cover the rear part of the operator's head, neck and chest, which first and second string also have a length such that they can be arranged, at the end of the wearing-on of the hood, around the chest and connected, in particular knotted, to one another at the front portion of said enveloping main body. suitable to be worn, in sterile form, by an operator, in particular in an operating room or in a clean room, over a helmet, which protective hood is supplied in folded form and includes: ▪ a front vision lens, apt to be positioned, in use, at least at the operator's eyes, ▪ an enveloping main body, fixed to said vision lens at a peripheral region of the latter and configured to cover completely the operator's head, neck and an upper part of the chest, which enveloping main body comprises a front portion and a rear portion connected and made integral by two opposite side portions (13, 14), ▪ a front vision lens, apt to be positioned, in use, at least at the operator's eyes, ▪ an enveloping main body, fixed to said vision lens at a peripheral region of the latter and configured to cover completely the operator's head, neck and an upper part of the chest, which enveloping main body comprises a front portion and a rear portion connected and made integral by two opposite side portions (13, 14), characterized in that it further comprises ▪ a first and a second lateral string, each one fixed, at a respective terminal end, on said rear portion of said enveloping main body, said first and second string being arranged on opposite sides with respect to a longitudinal axis of the hood, which first and second string are configured to be grasped by the operator during wearing of the hood in order to unwind said rear portion and bring it to cover the rear part of the operator's head, neck and chest, which first and second string also have a length such that they can be arranged, at the end of the wearing-on of the hood, around the chest and connected, in particular knotted, to one another at the front portion of said enveloping main body. ▪ a first and a second lateral string, each one fixed, at a respective terminal end, on said rear portion of said enveloping main body, said first and second string being arranged on opposite sides with respect to a longitudinal axis of the hood, which first and second string are configured to be grasped by the operator during wearing of the hood in order to unwind said rear portion and bring it to cover the rear part of the operator's head, neck and chest, which first and second string also have a length such that they can be arranged, at the end of the wearing-on of the hood, around the chest and connected, in particular knotted, to one another at the front portion of said enveloping main body. which first and second string are configured to be grasped by the operator during wearing of the hood in order to unwind said rear portion and bring it to cover the rear part of the operator's head, neck and chest, which first and second string also have a length such that they can be arranged, at the end of the wearing-on of the hood, around the chest and connected, in particular knotted, to one another at the front portion of said enveloping main body.