['The aim of the present study is to investigate serum BDNF levels in older depressed patients as compared to healthy elderly controls.', 'Twenty-nine elderly subjects with major depression and 42 healthy older adults were enrolled to this study. All depressed patients were antidepressant-free for at least 1 month prior clinical and laboratorial assessments. Serum BDNF levels were determined by sandwich ELISA.', 'BDNF levels were lower in elderly depressed patients as compared to controls (P=0.034). Patients with late-onset depression had the lowest BDNF level (median 478.5, interquartile range 373.5-740.9 pg/l) when compared to early-onset depression (median 620.7, interquartile range 366.1-971.9 pg/l) and healthy controls (median 711.3, interquartile range 534.7-1181.0 pg/l) (P<0.03).'] Is serum brain-derived neurotrophic factor level reduced in antidepressant-free patients with late-life depression?