A gas turbine engine comprising: an annular bypass passage for channelling air from a fan flow; a main gas path passage for receiving a flow having a swirl component in a given direction; and an exhaust mixer adapted to receive the flow from the main gas path passage having the swirl component in the given direction, the exhaust mixer comprising: an annular wall defining a central longitudinal axis, the annular wall having opposed upstream and downstream ends (36, 38) and defining a plurality of circumferentially distributed alternating inner and outer lobes (42, 44), with each inner lobe protruding into the main gas path passage, and each outer lobe protruding into the annular bypass passage, each outer lobe having a crest line extending substantially longitudinally through each radially outermost point of the outer lobe and a base defined between spaced apart wall portions of the outer lobe at an upstream end of the crest line, at least a downstream portion of the crest line being curved with respect to a circumferential direction of the exhaust mixer, characterized in that the crest line of each outer lobe is curved such as to define a circumferential offset with respect to the longitudinal axis in the same direction as that of the swirl component of the flow from the main gas path passage in order to maintain or increase the swirl in the turbine exhaust flow. an annular bypass passage for channelling air from a fan flow; a main gas path passage for receiving a flow having a swirl component in a given direction; and an exhaust mixer adapted to receive the flow from the main gas path passage having the swirl component in the given direction, the exhaust mixer comprising: an annular wall defining a central longitudinal axis, the annular wall having opposed upstream and downstream ends (36, 38) and defining a plurality of circumferentially distributed alternating inner and outer lobes (42, 44), with each inner lobe protruding into the main gas path passage, and each outer lobe protruding into the annular bypass passage, each outer lobe having a crest line extending substantially longitudinally through each radially outermost point of the outer lobe and a base defined between spaced apart wall portions of the outer lobe at an upstream end of the crest line, at least a downstream portion of the crest line being curved with respect to a circumferential direction of the exhaust mixer, characterized in that the crest line of each outer lobe is curved such as to define a circumferential offset with respect to the longitudinal axis in the same direction as that of the swirl component of the flow from the main gas path passage in order to maintain or increase the swirl in the turbine exhaust flow. each inner lobe protruding into the main gas path passage, and each outer lobe protruding into the annular bypass passage, each outer lobe having a crest line extending substantially longitudinally through each radially outermost point of the outer lobe and a base defined between spaced apart wall portions of the outer lobe at an upstream end of the crest line, at least a downstream portion of the crest line being curved with respect to a circumferential direction of the exhaust mixer, characterized in that the crest line of each outer lobe is curved such as to define a circumferential offset with respect to the longitudinal axis in the same direction as that of the swirl component of the flow from the main gas path passage in order to maintain or increase the swirl in the turbine exhaust flow.