OBJECTIVE: To evaluate Transforming Growth Factor β[sub 1] (TGF-β[sub 1]) plasma concentrations and the possible relationship between this growth factor and various hormones in obese women. DESIGN: Case-control study. SETTING: Outpatient's Service for the Prevention and Treatment of Obesity at the University Hospital. SUBJECTS: Twenty-five women with mild to moderate obesity, and 15 non-obese healthy women were used as controls. MEASUREMENTS: Evaluation of TGF-β[sub 1], insulin, prolactin, sex-hormone binding globulin, androstenedione, free triiodothyronine, free tetraiodothyronine, thyroid-stimulating hormone, dehydroepiandrosterone-sulfate, testosterone, insulin-like growth factor 1, cortisol and adrenocorticotropic hormone plasma concentrations in obese women. Blood samples were taken from fasting subjects for the determination of the above parameters. RESULTS: In obese women plasma TGF-β[sub 1] concentrations were lower than in controls. The obese subjects also had lower GH, IGF-1 and SHBG plasma concentrations and increased insulinaemia. A positive correlation was found between TGF-β[sub 1] and both IGF-1 (r = 0.52; P < 0.01) and DHEA-S (r = 0.43; P < 0.05), while a negative correlation was found between TGF-β[sub 1] and SHBG (r = -0.49; P < 0.05). CONCLUSIONS: The reduction in TGF-β[sub 1], an antilipogenic factor, may play a role in the pathogenesis of obesity and could be involved in the development of some obesity-related endocrine alterations. [ABSTRACT FROM AUTHOR]