Levels of hypertension treatment and control have been noted to vary between Europe and North America, although direct comparisons with similar methods have not been undertaken. In this study, we sought to estimate the relative impact of hypertension treatment strategies in Germany, Sweden, England, Spain, Italy, Canada, and the United States by using sample surveys conducted in the 1990s. Hypertension was defined as a blood pressure of 160/95 mm Hg or 140/90 mm Hg, plus persons taking antihypertensive medication. "Controlled hypertension" was defined as a blood pressure less than threshold among persons taking antihypertensive medications. Among persons 35 to 64 years, 66% of hypertensives in the United States had their blood pressure controlled at 160/95 mm Hg, compared with 49% in Canada and 23% to 38% in Europe. Similar discrepancies were apparent at the 140/90 mm Hg threshold, at which 29% of hypertensives in the United States, 17% in Canada, and </=10% in European countries had their blood pressure controlled. At the 140/90 mm Hg cutpoint, two thirds to three quarters of the hypertensives in Canada and Europe were untreated compared with slightly less than half in the United States. Although guidelines vary among countries, resulting in different case definitions, this does not account entirely for the varying success of different national control efforts. Low treatment and control rates in Europe, combined with a higher prevalence of hypertension, could contribute to a higher burden of cardiovascular disease risk attributable to elevated blood pressure compared with that in North America.