An anvil assembly comprising: an anvil (220; 320; 420; 520; 620; 720; 820; 920; 1020; 1120; 1220; 1320) configured for providing resistance to staples during the stapling operation of a surgical stapler, the surgical stapler comprising a proximal end and a distal end, wherein the proximal end is proximate to the user in use and the distal end is distal from the user in use; and a shaft (250; 350; 450; 550; 650; 750; 850; 950; 1150; 1250) to which the anvil is attached; wherein the anvil is attached to the shaft by one or more supporting arms (260; 360; 361; 460; 461; 560; 561; 660; 661; 662; 663; 760; 761; 762; 1151), wherein the anvil assembly is locatable at the distal end of the surgical stapler, wherein the anvil is configured to be actuated between a deployed state and a collapsed state, wherein the anvil is attached to the shaft in both the deployed state and the collapsed state, wherein the anvil comprises a plurality of segments (230; 231; 330; 331; 332; 337; 338; 339; 340; 431; 530; 631; 632; 730; 731; 732; 830; 930; 931; 932; 938; 939) arranged end-to-end, wherein the anvil is elongated in the collapsed state, the anvil being elongated generally in a first direction (D 1), wherein the shaft extends in the first direction, wherein the area covered by the anvil is greater in the deployed state (A D) than the collapsed state (Ac) when viewed along the first direction, wherein the anvil is configured such that the segments rotate about a rotation axis along a second direction perpendicular to the first direction when the anvil is actuated between the deployed and the collapsed states, and wherein the anvil is configured such that adjacent segments pivot relative to each other about a pivot axis along a third direction (D 3) perpendicular to the second direction when the anvil is actuated between the deployed and collapsed states; wherein when in the deployed state the supporting arm(s) is/are orientated substantially perpendicular to the first direction. an anvil (220; 320; 420; 520; 620; 720; 820; 920; 1020; 1120; 1220; 1320) configured for providing resistance to staples during the stapling operation of a surgical stapler, the surgical stapler comprising a proximal end and a distal end, wherein the proximal end is proximate to the user in use and the distal end is distal from the user in use; and a shaft (250; 350; 450; 550; 650; 750; 850; 950; 1150; 1250) to which the anvil is attached; wherein the anvil is attached to the shaft by one or more supporting arms (260; 360; 361; 460; 461; 560; 561; 660; 661; 662; 663; 760; 761; 762; 1151), wherein the anvil assembly is locatable at the distal end of the surgical stapler, wherein the anvil is configured to be actuated between a deployed state and a collapsed state, wherein the anvil is attached to the shaft in both the deployed state and the collapsed state, wherein the anvil comprises a plurality of segments (230; 231; 330; 331; 332; 337; 338; 339; 340; 431; 530; 631; 632; 730; 731; 732; 830; 930; 931; 932; 938; 939) arranged end-to-end, wherein the anvil is elongated in the collapsed state, the anvil being elongated generally in a first direction (D 1), wherein the shaft extends in the first direction, wherein the area covered by the anvil is greater in the deployed state (A D) than the collapsed state (Ac) when viewed along the first direction, wherein the anvil is configured such that the segments rotate about a rotation axis along a second direction perpendicular to the first direction when the anvil is actuated between the deployed and the collapsed states, and wherein the anvil is configured such that adjacent segments pivot relative to each other about a pivot axis along a third direction (D 3) perpendicular to the second direction when the anvil is actuated between the deployed and collapsed states; wherein when in the deployed state the supporting arm(s) is/are orientated substantially perpendicular to the first direction.