From my experience, yes. If a ringworm is not treated it can leave a scar. When I begin working with children, I got my first ringworm I know it sound silly but I had no idea what it was. I just thought it would go away. After a few weeks (not even a whole year) I was so annoyed by it that I asked a pharmacist what it was and discovered it was a ringworm. Well even with treatment it still left a dark scar and it was only a few weeks. I got rid of that scar with some bleaching cream. I recommend a cream called BlackandWhite.