Clin Exp Dermatol. 2009 Jun 22; Law MP, Chuh AA, Molinari N, Lee ASummary Background. The association between diet and acne vulgaris has long been suggested but remains unproven in western medicine. In contrast, the diet-acne relationship is considered important in traditional Chinese medicine (TCM). Aim. To investigate the association between diet and acne, using a TCM approach. Methods. Using a cross-sectional study of 322 entrants to a university in Hong Kong, China, we examined the participants' clinical severity of acne using the Global Acne Grading System and the participants' yin and yang scores using a quantitative method. We then divided them into two groups, a yin-predominant group (yin-PG) and a yang-predominant group (yang-PG) before the diet-acne relationship was investigated. Results. In total, 82 (25.2%) participants were in the clinical acne group and 240 (74.5%) were in the reference group. There were 155 (48.1%) participants in the yin-PG and 167 (51.9%) in the yang-PG group. No association of diet and acne was found when the participants were considered as a homogenous group. In yin-PG, intake of foods from street stalls (P = 0.04) was significantly associated with a lower incidence of acne. In yang-PG, the intake of desserts (P = 0.04) and fresh fruit juices (P = 0.02) was significantly associated with a higher incidence of acne, whereas the intake of dairy and soy products (P = 0.04) was significantly associated with a lower incidence of acne. Conclusions. The application of a TCM approach led to the detection of significant associations between diet and the incidence of acne.