The baseline characteristics, possibly related to cardiovascular outcome, in 94 Romanian hypertensive men and 168 women over the age of 80 entered into the Hypertension in the Very Elderly Trial (HYVET) were compared with those in 725 men and 1128 women entered into the trial in the rest of Western and Eastern Europe (mainly Russia and Bulgaria). There was a tendency for more women in the Romanian subjects (66.7% versus 60.9% (P = 0.08)) and therefore all comparisons were adjusted for this non significant difference. The Romanian subjects were slightly younger, had more previous hypertension, but more previous strokes than the rest of Europe, and consumed a similar amount of alcohol. The Romanian subjects were, on average, lighter and shorter. Romanians had higher mean concentrations of blood urea and glucose and higher concentrations of HDL cholesterol. Total cholesterol was, on average, lower in Romanian subjects than was serum creatinine. Serum sodium, blood hematocrit and hemoglobin were all, on average, lower in Romanian subjects. The Romanian subjects were recruited from predominantly rural areas and it is hypothesised that their diet may have contained less salt, iron and other haematinics. Calorie restriction, compared to the rest of Europe, may have resulted in lower stature and weight but recent increases in calorie intake may have resulted in the increasing average blood glucose in both sexes. DDT is known to block the uptake of HDL cholesterol by the liver and may explain the increased HDL concentrations in Romania. Some of these biochemical differences may reflect different methodologies employed in Romanian laboratories, but we could not confirm this possibility.