Treatment device for use in the simultaneous heat-therapeutic treatment of both breasts (31, 32) of a female patient, in particular for use in the treatment after surgical interventions and/or of injuries and/or of inflammations, with - a first and a second sleeve (2, 3), each of which is at least substantially hemispherically shaped and with each of which a breast (31; 32) can be largely or completely covered, the first sleeve having at least one first flexible material layer and at least one second flexible material layer, which form a first heat transfer body, and the second sleeve having at least one third flexible material layer and at least one fourth flexible material layer, which form a second heat transfer body, the first and second flexible material layers of the first sleeve and the third and fourth flexible material layers of the second sleeve respectively delimiting one or more flow spaces (12, 12') through which a heat-transmitting fluid can flow and being connected to one another by a multiplicity of connecting devices (4, 4', 4", 4′′′); - an attachment device connectable at a first end to the first sleeve and at a second end to the second sleeve, in the region of the sternum of the female patient when the treatment device is placed on the female patient during treatment; - a first, flexible elongate support device connectable at a first end to the first sleeve and at a second end to the second sleeve such that the first support device, when positioned on the neck of the female patient, allows the first and second sleeves (2, 3) to be adjusted in height; - a second, flexible elongate support device which can be connected at a first end to the first sleeve and at a second end to the second sleeve, so that the second support device, when it encloses the thorax of the female patient, can fix the first sleeve to a first breast and the second sleeve to a second breast of the female patient; - at least one first supply line for supplying a heat-transferring fluid to the first and/or second heat transfer body; - at least one second supply line for discharging a heat transfer fluid from the first and/or second heat transfer body; and - a transfer device by which the first heat transfer body is connectable to the second heat transfer body so that the heat transfer fluid can flow from the first into the second heat transfer body and vice versa, characterized in that the transfer device is arranged in the region of the sternum of the female patient when the treatment device is arranged on the female patient during treatment. - a first and a second sleeve (2, 3), each of which is at least substantially hemispherically shaped and with each of which a breast (31; 32) can be largely or completely covered, the first sleeve having at least one first flexible material layer and at least one second flexible material layer, which form a first heat transfer body, and the second sleeve having at least one third flexible material layer and at least one fourth flexible material layer, which form a second heat transfer body, the first and second flexible material layers of the first sleeve and the third and fourth flexible material layers of the second sleeve respectively delimiting one or more flow spaces (12, 12') through which a heat-transmitting fluid can flow and being connected to one another by a multiplicity of connecting devices (4, 4', 4", 4′′′); - an attachment device connectable at a first end to the first sleeve and at a second end to the second sleeve, in the region of the sternum of the female patient when the treatment device is placed on the female patient during treatment; - a first, flexible elongate support device connectable at a first end to the first sleeve and at a second end to the second sleeve such that the first support device, when positioned on the neck of the female patient, allows the first and second sleeves (2, 3) to be adjusted in height; - a second, flexible elongate support device which can be connected at a first end to the first sleeve and at a second end to the second sleeve, so that the second support device, when it encloses the thorax of the female patient, can fix the first sleeve to a first breast and the second sleeve to a second breast of the female patient; - at least one first supply line for supplying a heat-transferring fluid to the first and/or second heat transfer body; - at least one second supply line for discharging a heat transfer fluid from the first and/or second heat transfer body; and - a transfer device by which the first heat transfer body is connectable to the second heat transfer body so that the heat transfer fluid can flow from the first into the second heat transfer body and vice versa,