Stirrup for horse-riding saddles, comprising: - a support element , to support a user's foot, - and an open arch extending from the opposite ends of said support element, said open arch in turn comprising: - a first load-bearing half-arch extending from a first lateral portion of said support element and comprising an attachment portion configured for fastening a stirrup strap, - and a second containment half-arch , extending from a second lateral portion of said support element , opposite to said first lateral portion , said second half-arch comprising a lower part configured to be constrained to said support element , and an upper part extending from said lower part up to the proximity of said attachment portion , said second half-arch comprising a single body of elastically deformable plastic material defining said lower part and said upper part , said upper part extending along a development curved line (X), said upper part extending from its lower end , being a part of the single body , the lower end of which is located substantially in correspondence with an upper surface of said support element , along said curved line (X), up to an upper end thereof positioned in proximity to, or in contact with, a facing end of said attachment portion , the cross-sectional area of said upper part decreasing in the direction which runs from said lower end to said upper end , characterized in that said upper part has a transversal section at any of its points, orthogonal to said development curved line (X), having a circular or oval profile. - a support element , to support a user's foot, - and an open arch extending from the opposite ends of said support element, said open arch in turn comprising: - a first load-bearing half-arch extending from a first lateral portion of said support element and comprising an attachment portion configured for fastening a stirrup strap, - and a second containment half-arch , extending from a second lateral portion of said support element , opposite to said first lateral portion , said second half-arch comprising a lower part configured to be constrained to said support element , and an upper part extending from said lower part up to the proximity of said attachment portion , - a first load-bearing half-arch extending from a first lateral portion of said support element and comprising an attachment portion configured for fastening a stirrup strap, - and a second containment half-arch , extending from a second lateral portion of said support element , opposite to said first lateral portion , said second half-arch comprising a lower part configured to be constrained to said support element , and an upper part extending from said lower part up to the proximity of said attachment portion , said second half-arch comprising a single body of elastically deformable plastic material defining said lower part and said upper part , said upper part extending along a development curved line (X), said upper part extending from its lower end , being a part of the single body , the lower end of which is located substantially in correspondence with an upper surface of said support element , along said curved line (X), up to an upper end thereof positioned in proximity to, or in contact with, a facing end of said attachment portion , the cross-sectional area of said upper part decreasing in the direction which runs from said lower end to said upper end , characterized in that said upper part has a transversal section at any of its points, orthogonal to said development curved line (X), having a circular or oval profile. <EOS>