Iron (3 mg) was added as ferrous sulphate to 2 dl red wine, white wine and 7% alcohol and its absorption was then measured in 38 fasting male subjects. (The original concentrations of iron in the two wines were low, being 1.01-1.08 mg/l (red wine) and 0.13-0.20 (white wine]. The geometric mean absorption from red wine was only 20% of that from the alcohol solution whilst more than 4 times as much was absorbed from white wine as from the alcohol. Direct comparison showed greater absorption from white wine (10.4%) than from red wine (4.4%). Removal of about 80% of the polyphenols in red wine increased the geometric mean iron absorption from 1.9% to 3.6%. In vitro experiments indicated that iron was less soluble and less dialysable in red wines than in white wines. This was possibly due to the binding of iron to polyphenols in red wines. Electrophoretic studies suggested that the iron in white wines was complexed to hydroxycarboxylic acids.