The blood and plasma concentrations of thiamin and thiamin phosphate esters were determined concomitantly by high-performance liquid chromatography (HPLC) in 22 patients with alcoholic liver cirrhosis, and also in 10 of them 24 hr after a 100 mg thiamin i.m. injection. Sixteen patients were abstaining from alcohol at the time of the study, 6 were currently misusing alcohol. The control group included 30 healthy volunteers, of whom 10 were given the same thiamin injection as the patients. Blood thiamin diphosphate was the only compound decreased in the abstaining patients compared to controls (70.9 +/- 21.9 nmol/l vs. 84.4 +/- 19.0 nmol/l), but all thiamin compounds in blood and plasma were decreased in the misusing patients. All thiamin compounds (except blood monophosphate) were also significantly lower in the misusing than in the abstaining patients (plasma thiamin: 5.3 +/- 1.3 vs. 11.7 +/- 8.3 nmol/l; plasma monophosphate: 1.0 +/- 1.1 vs. 4.1 +/- 2.9 nmol/l; blood diphosphate: 45.7 +/- 18.3 vs. 70.9 +/- 21.9 nmol/l). Thiamin phosphorylation ratio was decreased in the patients after thiamin administration compared to controls (2.83 +/- 0.74 vs. 3.68 +/- 0.58). Plasma thiamin was higher in the abstaining patients than in the controls (11.7 +/- 8.4 nmol/l vs. 7.3 +/- 2.5 nmol/l), and above the mean + 2 SD of the controls in 31% of the abstaining patients. In conclusion, current ethanol misuse is associated with low thiamin concentrations, and liver cirrhosis is associated with a decreased thiamin diphosphate concentration and thiamin phosphorylation.