Excess scar formation secondary to traumatic or surgical injuries can have devastating consequences, ranging from body disfigurement to organ dysfunction. Hypertrophic scars and keloids are skin fibrotic conditions that can be caused by minor insults to skin, such as acne or ear piercing, or by severe injuries such as burns. Differences between keloids, hypertrophic scars and normal scars include distinct scar appearance, histologic morphology and cellular function in response to growth factors. Recent advances in our understanding of the wound healing process reveal possible causes for hypertrophic scars and keloids. This information might assist in the development of efficacious treatment for hypertrophic scar and keloid formation.