Dehydroepiandrosterone (D) and dehydroepiandrosterone sulfate (DS) dynamics were studied in three obese female subjects following a single injection of [4-14C]D and [7α-3H]-DS tracers. Dynamic parameters were calculated simultaneously by both the urinary and blood method of compartmentalization. Estimates for the urinary secretion and production rates of D were found to be high, and those of DS varied within normal range. Calculation of the conversion factors, ρDDS and ρDSD, by the urinary method revealed a normal extra-glandular DS→ D conversion, while that for D → DS appeared deficient in obese female subjects. Estimates of inner and outer pool distribution volumes were extremely increased for free D; in contrast to this, moderately increased inner and decreased outer pool volumes of DS were observed. The metabolic clearance rates of D were normal or decreased and those for DS were greater than normal. The blood production rates of both D and DS were higher in obese female subjects than those estimated for normal women in our previous study.These observations suggest a considerable uptake of unconjugated D by adipose tissue, an overall poor D → DS conversion and an accelerated DS metabolism in obese female subjects.