Di-(2-ethylhexyl)phthalate (DEHP) is the most commonly used plasticizer in flexible polyvinylchloride formulations, and is a widespread ubiquitous environmental contaminant. A potential role of exposure to DEHP and its primary metabolite, monoethylhexylphthalate (MEHP), on women's reproductive function is suggested in the current study. The aim of the study was to test serum concentrations of DEHP and/or MEHP in women with uterine fibromatosis. Two groups of women were enrolled in the study: (i) women with uterine fibromatosis undergoing surgical menopause (n = 15) and (ii) healthy women (n = 20). Serum DEHP and MEHP concentrations were measured by high-performance liquid chromatography. Serum MEHP distribution was found to be non-Gaussian (p = 0.001) while serum DEHP distribution was compatible with a normal curve (p = 0.141). Patients with uterine fibromatosis showed significantly lower serum MEHP concentrations (median [interquartile range]: 0 [0-0] microg/ml, range: 0-0.57 microg/ml) than controls (0.42 [0-0.51] microg/ml, range: 0-1.20 microg/ml, z = -2.93, p = 0.0034). Likewise, serum DEHP concentrations in women with fibromatosis were found to be significantly lower than in controls (patients: 0.27 +/- 0.096 microg/ml (mean +/- standard deviation (SD)), range: 0.14-0.59 microg/ml vs. controls: 0.30 +/- 0.14 microg/ml (mean +/- SD), range: 0-0.63 microg/ml; t = 3.212, df = 33, difference: -0.325 (95% confidence interval: -0.5309, -0.1191), p = 0.0029). In conclusion, the present findings indicate for the first time that serum DEHP and MEHP concentration are lower in women with uterine fibromatosis, suggesting a possible correlation between phthalate esters and fibromatosis pathology.