Smoking is known to increase the risk of developing systemic lupus erythematosus (SLE), but the results of a cross-sectional study of 730 Chinese patients with SLE, including 65 current or former smokers, suggest that smoking could also worsen renal disease. After adjustment for age and sex, several features were significantly more frequent in smokers than nonsmokers: photosensitivity (35.9% versus 18%; P = 0.006), nephropathy (59.4% versus 39.8%; P = 0.011), and proteinuria (54.7% versus 35.2%; P = 0.010).