Serum C19 conjugates, specifically 3 alpha-androstanediol glucuronide (3 alpha G), reflect peripheral androgen action through the action of 5 alpha-reductase activity. The origin of 5 alpha-reduced C19 conjugates has been controversial and it has been suggested that they are derived primarily from adrenal androgens. We examined concentrations of 3 alpha G, 3 alpha-androstanediol sulphate (3 alpha S), androsterone glucuronide (AoG) and androsterone sulphate (AoS) in 40 hirsute hyperandrogenic women. These patients were divided into four groups based upon individual, combined or normal concentrations of the adrenal androgens dehydroepiandrosterone (DHEAS) and 11 beta-hydroxy-androstenedione. Testosterone, unbound testosterone and androstenedione were similar in these groups. Serum 3 alpha G was equally high in all groups and was correlated significantly with hirsutism, while the other conjugates were not. Androsterone glucuronide was raised in all groups but was higher in patients with raised DHEAS. Serum 3 alpha S was raised in all groups and was higher where both adrenal androgens were raised. Serum AoS was highly correlated with DHEAS. Serum 3 alpha G was correlated with unbound testosterone and androstenedione but not with the adrenal androgens. The glucuronide conjugates were correlated with one another as were the sulphate conjugates but glucuronides and sulphates were not correlated. These data confirm ovarian and adrenal dependency of C19 conjugates. Serum 3 alpha G appears to reflect hirsutism most accurately and is least dependent on adrenal androgens in patients with mixed hyperandrogenism.