Background Seborrheic dermatitis (SD) is a common, chronic, inflammatory skin disorder, yet few studies have reported its clinical characteristics, or addressed its effect on quality of life (QoL). This study assesses the clinical characteristics and QoL of SD patients in China. It also identifies the clinical, demographic and environmental factors that may influence QoL. Methods Three hundred twelve SD outpatients from 9 hospitals completed a survey. QoL was measured with the dermatology-specific instrument Skindex-29. We collected social demographic characteristics and disease severity, and conducted logistic regression to determine the factors associated with QoL impairment. Results 67.3% of the patients were females. The mean Skindex-29 overall score was 33.97 (SD = 20.55). The breakdown was 40.79 (SD = 24.24) for emotions, 32.83 (SD = 19.84) for symptoms and 28.3 (SD = 23.24) for functioning. 48.1% had severe emotional problems. Logistic regression analysis showed that BMI less than 25 (OR = 0.223; 95% CI: 0.072-0.692;P = 0.009), skin disease-related hospitalization (OR = 6.882; 95% CI:1.767-26.795;P = 0.005), environmental PM 10 levels above 120 mu g/m(3)(OR = 3.386; 95% CI: 1.253-9.15;P = 0.016) and severe disease conditions (OR = 4.438; 95% CI:1.26-15.626;P = 0.02) were risk factors for severe emotional impairment. Moreover, skin disease-related hospitalization (OR = 6.057; 95% CI:1.351-27.149;P = 0.019), environmental PM 10 levels between 70 and 120 mu g/m(3)(OR = 6.317; 94% CI: 1.704-23.42;P = 0.006), moderate (OR = 2.388; 95% CI: 1.272-4.487;P = 0.007) and severe disease conditions (OR = 5.732; 95% CI: 1.838-17.88;P = 0.003) were each risk factors for overall severe impairment. Conclusion In China, nearly half of SD patients had severely emotional problems. Disease severity, BMI, dermatologic hospitalization, and ambient PM 10 levels are each risk factors for QoL impairment in SD patients. These implications are alarming, and warrant public health attention in SD disease management.