Objective To assess trends in blood pressure (BP) levels, prevalence, awareness, and control of hypertension in the Czech population from 1985 to 2000/01. Design Five independent cross-sectional population surveys conducted in 1985,1988,1992,1997/98, and 2000/01. Setting Six, mostly rural, districts of the Czech Republic (Praha-vychod, Benesov, Pardubice, Chrudim, Cheb, and Jindrichuv Hradec). Participants Men and women aged 25-64 years randomly selected from six districts using the National Population Register/General Health Insurance Company Register (covering, by law, all citizens). The total number of participants was 11 726. Main outcome measures We assessed the mean systolic BP, diastolic BP and pulse pressure, prevalence of hypertension (systolic BP greater than or equal to 140 mmHg and/or diastolic BP greater than or equal to 90 mmHg, or current treatment with anti hypertensive drugs), awareness, treatment, and control of hypertension. Results Mean systolic BP, diastolic BP, and pulse pressure decreased significantly over a period of 15/16 years. This was associated with a significant decrease in the prevalence of hypertension (from 47.1 to 39.1%, P < 0.001) and with an increase in its awareness (from 49.5 to 67.2%, P < 0.001), use of anti hypertensive medication (from 29.3 to 49.3%, P < 0.001), and hypertension control (from 3.9 to 17.0%, P < 0.001). Despite having lower BP values and prevalence of hypertension, females showed higher awareness of the disease, and were more frequently taking anti hypertensive medication, and their hypertension was better controlled. Conclusion The reduction in population BP and improved control of hypertension may have contributed to the decrease in cerebrovascular and coronary heart disease mortality in the Czech Republic. The positive longitudinal changes seen in the MONICA regions need not necessarily reflect the situation in the country as a whole. The situation is far from being optimal; a major problem is inadequate treatment of hypertension.