A combustion chamber comprising an upstream ring structure (43A, 43B), a downstream ring structure (54, 56) and a plurality of circumferentially arranged combustion chamber segments (58, 60), each combustion chamber segment (58, 60) extending the full length of the combustion chamber, each combustion chamber segment (58, 60) comprising a frame structure and an inner wall, the frame structure and the inner wall being integral, an upstream end of each combustion chamber segment (58, 60) being secured to the upstream ring structure (43A, 43B) and a downstream end of each combustion chamber segment (58, 60) being mounted on the downstream ring structure (54, 56), wherein the upstream end of each combustion chamber segment (58, 60) comprises a surface having a plurality of circumferentially spaced radially extending holes, the upstream ring structure (43A, 43B) having a plurality of circumferentially spaced holes (116A, 116B) extending radially through a portion abutting the surface of the upstream end of each combustion chamber segment (58, 60) and each combustion chamber segment (58, 60) being removably secured to the upstream ring structure (43A, 43B) by a plurality of fasteners locatable in the holes in the combustion chamber segment (58, 60) and corresponding holes (118A, 118B) in the upstream ring structure (43A, 43B), each combustion chamber segment (58, 60) having a hole cooperating with a corresponding hole in the upstream ring structure (43A, 43B) to circumferentially position the combustion chamber segment (58, 60) relative to the upstream ring structure (43A, 43B) and each combustion chamber segment (58, 60) having a further hole cooperating with a further corresponding hole in the upstream ring structure (43A, 43B) to allow relative circumferential thermal expansion between the combustion chamber segment (58, 60) and the upstream ring structure (43A, 43B) wherein one of the further hole and the further corresponding hole being circumferentially slotted, wherein the upstream ring structure (43A, 43B) having a plurality of first holes and a plurality of second holes, the first and second holes (116A, 116B) being arranged circumferentially alternately around the upstream ring structure (43A, 43B), each first hole has the same diameter as the diameter of the holes in the frame structure of the combustion chamber segments (58, 60), each second hole is circumferentially slotted, each first hole is aligned axially and circumferentially with a hole in a corresponding combustion chamber segment (58, 60) and each second hole is aligned axially with another hole in the corresponding combustion chamber segment (58, 60) to allow relative circumferential thermal expansion between the combustion chamber segment (58, 60) and the upstream ring structure (43A, 43B) or the frame structure at the upstream end of each combustion chamber segment having a first hole and a circumferentially spaced second hole, the first and second holes of the combustion chamber segments being arranged circumferentially alternately, each first hole has the same diameter as the diameter of the holes in the upstream ring structure, each second hole is circumferentially slotted, each first hole is aligned axially and circumferentially with a corresponding hole in the upstream ring structure and each second hole is aligned axially with a corresponding hole in the upstream ring structure to allow relative circumferential thermal expansion between the combustion chamber segment and the upstream ring structure.