Ephelides are one of the most common lesions of skin pigmentation mainly on sun-exposed skin. Although they are benign pigmented spots, ephelides cause an increasing concern because of the wide-spreading cosmetic attention of society and possible association with skin cancer. However, there have been few reports on the prevalence of ephelides. The objective of this study was to estimate the prevalence of ephelides and the possible role of genetic factors in the pathogenesis of ephelides in the Han Chinese adolescents. Assessment of the skin was conducted in college students of the Anhui Medical University in China. Information on common skin conditions including ephelides were collected from 9697 Han Chinese college students. A total of 1,841 ephelides cases and 582 normal controls were identified and they, along with their first-degree relatives, provided information on ephelides conditions. The odds ratio was used to estimate the relative risk of ephelides between the first-degree relatives of cases and controls. The overall prevalence of ephelides was estimated to be 19.0% in college students. Ephelides are more common in female students (26.1%) than in males (12.1%; chi(2) = 06.7, P < 0.05). The mean ages of onset for males and females were 12.42 years (+/-4.61) and 12.88 years (+/-3.90; t = 2.11, P < 0.05), respectively. Positive family history was observed in 932 of the 1,841(50.6%) patients. The severity of ephelides in females of light skin was found to be significantly higher than that in males with skin of similar color (U = 3.904, P < 0.001). The risk of having ephelides among first-degree relatives of cases was significantly higher than that for the relatives of normal controls (odds ratio 5.75, 95% confidence interval (CI): 4.61-7.18, P < 0.001). Our study provided the first information on the prevalence of ephelides in Chinese adolescents and suggests that familial factors are important in determining individual susceptibility to ephelides.