A treatment apparatus for treating a skin lesion on skin of a patient, the apparatus comprising a source of electromagnetic radiation (16), a guide (6, 20) to guide the electromagnetic radiation to the skin lesion (25) and a control apparatus (1), the control apparatus (1) being arranged so as to cause the source (16) and the guide (6, 20) to: provide an initial burst of electromagnetic radiation to the skin lesion (25) to heat it to a first temperature selected by the control apparatus (1); cease providing electromagnetic radiation to the skin lesion (25) for a period; and provide a further burst of electromagnetic radiation to the skin lesion (25) so as to maintain the temperature of the skin lesion within a temperature range selected by the control apparatus (1). The apparatus may comprise a temperature sensor (24) which detects the temperature of the patient’s skin, typically the skin lesion.