A cosmetic method of regenerating the skin in the region of a stretch mark is disclosed. The method comprises operating a source of thermal energy with a low thermal time constant, and directing it at the surface of the skin adjacent to and within a stretch mark forming first and second adjacent regions of thermally-modified tissue. The first region is adjacent to, and overlies, the second region, and the first region is thermally modified to a greater extend than the second region such that, following treatment, the width of the stretch mark is reduced and the reticular architecture of the dermis in the stretch mark is at least partially restored.