['To evaluate the impact of elevated serum Δ4A levels on the hormonal and metabolic features of the different phenotypes of PCOS.', '1276 women with PCOS according to the Rotterdam criteria were included, in whom serum hormonal levels were determined.', 'In PCOS women as a whole, as well as in patients presenting clinical and/or biochemical hyperandrogenemia (phenotypes I and II), Δ4A levels >3.8 ng/ml were positively related to LH, LH/FSH ratio, T, DHEAS, 17 OH progesterone and FAI and negatively related to T/Δ4A ratio. In the milder phenotype III, a positive correlation between Δ4A levels >3.8 ng/ml and T, DHEAS, 17 OH progesterone and FAI and a negative one between increased Δ4A and T/Δ4A ratio were reported. In the whole PCOS group with androstenedione >3.8 ng/ml, an increased ovarian volume was observed, while a greater mean follicular number was found only in phenotypes I and II.'] Is elevated serum androstenedione associated with a more severe phenotype in women with polycystic ovary syndrome ( PCOS )?