A surgical staple comprising: a backspan and a pair of deformable legs (612, 614) extending from the backspan and terminating in a penetrating end; wherein the backspan and deformable legs are formed from a wire having a curvilinear cross-section defining a major base axis (x) and a minor height axis (y) orthogonal to the major base axis (x) with a portion of the wire above the major base axis defining a first curved surface and a portion of the wire below the major base axis defining a third curved surface and a portion to left of the minor height axis defining a fourth curved surface and a portion to the right of the minor height axis defining a second curved surface, wherein the first, second, third and fourth curved surfaces are convex surfaces, the first curved surface is defined between points A and B, the second curved surface is defined between points B and C, the third curved surface is defined between points C and D, and the fourth curved surface is defined between points D and A and wherein the first, second, third and fourth curved surfaces are connected with arched edges, wherein the third curved surface is a mirror image of the first curved surface; wherein the first curved surface defines a first radius of curvature (r 3) at a point of intersection with the minor height axis, the second curved surface defines a second radius of curvature (r 2) at a point of intersection with the major base axis, the third curved surface defines a third radius of curvature (r 3) at a point of intersection with a minor height axis, and the fourth curved surface defines a fourth radius of curvature (r 1) at a point of intersection with the major base axis; wherein the first radius of curvature (r 3) of the first curved surface is greater than the fourth radius of curvature (r 1) of the fourth curved surface; and said surgical staple being characterised in that the first radius of curvature (r 3) of the first curved surface is less than the second radius of curvature (r 2) of the second curved surface. a backspan and a pair of deformable legs (612, 614) extending from the backspan and terminating in a penetrating end; wherein the backspan and deformable legs are formed from a wire having a curvilinear cross-section defining a major base axis (x) and a minor height axis (y) orthogonal to the major base axis (x) with a portion of the wire above the major base axis defining a first curved surface and a portion of the wire below the major base axis defining a third curved surface and a portion to left of the minor height axis defining a fourth curved surface and a portion to the right of the minor height axis defining a second curved surface, wherein the first, second, third and fourth curved surfaces are convex surfaces, the first curved surface is defined between points A and B, the second curved surface is defined between points B and C, the third curved surface is defined between points C and D, and the fourth curved surface is defined between points D and A and wherein the first, second, third and fourth curved surfaces are connected with arched edges, wherein the third curved surface is a mirror image of the first curved surface; wherein the first curved surface defines a first radius of curvature (r 3) at a point of intersection with the minor height axis, the second curved surface defines a second radius of curvature (r 2) at a point of intersection with the major base axis, the third curved surface defines a third radius of curvature (r 3) at a point of intersection with a minor height axis, and the fourth curved surface defines a fourth radius of curvature (r 1) at a point of intersection with the major base axis; wherein the first radius of curvature (r 3) of the first curved surface is greater than the fourth radius of curvature (r 1) of the fourth curved surface; and said surgical staple being characterised in that the first radius of curvature (r 3) of the first curved surface is less than the second radius of curvature (r 2) of the second curved surface.