An irradiation device for insertion into an orifice of the body to provide photodynamic therapy comprises: a housing moulded from a resilient material and adapted to be fully inserted and secured in the orifice, the housing enclosing an LED lamp system 22 and a power source 41 for powering the LED lamp system 22; wherein the device is independently operational while located in the orifice; characterised in that: the housing comprises a first housing part 2 for holding the power source 41 and a second housing part 4 for holding the LED lamp system 22, the first and second housing parts 2, 4 being separable and being preferably formed separately from the LED lamp system 22; and in that the first housing part 2 consists of a chamber 6 for holding the power source 41 and an opening 26 into the chamber 6 is provided through a resilient opening part 8, wherein the chamber 6 is closed when the first housing part 2 is joined to the second housing part 4.