A skin treatment device , in particular a hair removal device, comprising a light emission unit comprising a substrate and a plurality of first LED dies mounted on the substrate on an area of at least 0.2 c m2 , in particular of at least 1 c m2 , wherein the skin treatment device is arranged to activate the first LED dies to emit a treatment light pulse having a pulse length in particular in the range of between 10 ms and 300 ms and the first LED dies have a radiant flux such that a radiant fluence on the skin of a user of at least 1 J/cm 2 is achieved by application of the treatment light pulse, wherein the light emission unit has at least two selectable active areas (A1; A2) of first LED dies , where the selectable active areas (A1; A2) have different sizes, and at least three second LED dies are mounted on the substrate at locations suitable for visibly indicating each of the selectable active areas (A1; A2), wherein the second LED dies are disposed at corners or end points of the selectable active areas (A1; A2) of first LED dies or are mounted in close proximity to such corners or end points of the selectable active areas (A1; A2) of first LED dies ; and the skin treatment device further comprises a control unit for controlling the first and second LED dies , the control unit being arranged for activating only the first LED dies assigned to the selected active area (A1; A2) to emit the treatment light pulse and for activating only the second LED dies assigned to the selected active area (A1; A2) to emit visible light outside of the duration of the treatment light pulse to visibly indicate the selected active area (A1; A2). a light emission unit comprising a substrate and a plurality of first LED dies mounted on the substrate on an area of at least 0.2 c m2 , in particular of at least 1 c m2 , wherein the skin treatment device is arranged to activate the first LED dies to emit a treatment light pulse having a pulse length in particular in the range of between 10 ms and 300 ms and the first LED dies have a radiant flux such that a radiant fluence on the skin of a user of at least 1 J/cm 2 is achieved by application of the treatment light pulse, wherein the light emission unit has at least two selectable active areas (A1; A2) of first LED dies , where the selectable active areas (A1; A2) have different sizes, and at least three second LED dies are mounted on the substrate at locations suitable for visibly indicating each of the selectable active areas (A1; A2), wherein the second LED dies are disposed at corners or end points of the selectable active areas (A1; A2) of first LED dies or are mounted in close proximity to such corners or end points of the selectable active areas (A1; A2) of first LED dies ; and the skin treatment device further comprises a control unit for controlling the first and second LED dies , the control unit being arranged for activating only the first LED dies assigned to the selected active area (A1; A2) to emit the treatment light pulse and for activating only the second LED dies assigned to the selected active area (A1; A2) to emit visible light outside of the duration of the treatment light pulse to visibly indicate the selected active area (A1; A2). <EOS>