Purpose: This study investigated whether CYP1B1 gene expression was associated with blood lipids levels. Methods: Workers from a municipal waste incineration plant in Taiwan participated in a questionnaire survey and physical examination and provided fasting blood samples for blood lipid analysis. CYP1B1 gene expression in workers' leukocytes was determined with the real-time reverse transcriptase polymerase chain reaction method, and 112 workers were categorized into three groups (low-, medium-, and high-expression) by their relative CYP1B1 gene expression levels. Multiple regression analyses were used to assess the association between blood lipid parameter and CYP1B1 expression. Results: High-density lipoprotein (HDL) cholesterol was significantly lower in the high CYP1B1 expression group than in the low- and medium-expression groups (parameter estimate [standard error] = -7.16 [2.42] and -7.02 [2.46] mg/dL, respectively), after controlling for age, sex, CYP1B1 genotype, duration of employment, current number of cigarettes smoked per day, current alcohol drinking status, and body mass index. Triglycerides, low-density lipoprotein (LDL), and total cholesterol were not significantly different among the CYP1B1 expression groups. Furthermore, workers carrying the CYP1B1*3 allele had significantly higher mean HDL, LDL, and total cholesterol, respectively, than those with CYP1B1*1/*1. Conclusions: CYP1B1 expression was associated with decreased HDL cholesterol levels in incinerator workers. 穢 2008 Elsevier Inc. All rights reserved.