Although acne has traditionally been viewed as predominantly affecting adolescents, a significant and growing body of literature suggests an adult (i.e. post-adolescent) form of the disease. This review summarizes selected publications on post-adolescent acne, and discusses possible causes and treatment options. Recent epidemiological studies show that there appears to be an increase in post-adolescent acne, and that the disease is lasting longer and is requiring treatment well into the mid forties. There is good agreement that, unlike teenage acne, where males tend to show the most severe forms of the disease, post-adolescent acne mainly affects females (the lesions are frequently perioral and occur premenstrually) and that there are two forms of the disease. The terms 'persistent' and 'late onset' are now generally accepted as describing these two types. The causes of post-adolescent acne remain to be fully elucidated and hormones, colonization by resistant bacteria and the use of cosmetics have been put forward and debated in the literature. Additionally, some clues to the cause of post-adolescent acne may be gleaned from an individual's response to therapy. Perhaps one of the most intriguing explanations for the increase in this disease is the proposed relationship between increasing stress levels, androgen hormones and increasing levels of acne found in women in fast paced jobs.