Population surveys of the major cardiovascular risk factors were conducted in six districts of the Czech Republic in 1988 and 1992 as part of the WHO MONICA Project. One-percent independent random samples of the population aged 25-64 years were examined and investigated; in 1988, the survey included 1357 men and 1412 women (response rates of 85.5% and 88.4%, respectively); 1139 men and 1214 women with the response rate 71.2% and 75.0%, respectively, were enrolled in 1992. Over the four years, the mean levels of diastolic blood pressure rose from 83.8 mmHg to 85.5 mmHg (p < 0.001) in men; the rise in women from 80.7 mmHg to 81.6 mmHg was non-significant. Systolic blood pressure between the two surveys did not differ significantly. Mean total cholesterol levels declined from 6.24 mmol/l to 5.91 mmol/l (p < 0.001) in men and from 6.16 mmol/l to 5.87 mmol/l (p < 0.001) in women. Mean BMI decreased from 27.5 to 26.9 (p < 0.001) in men and from 27.4 to 26.5 (p < 0.001) in women. The authors assume that the significant decreases in cholesterolaemia and BMI may be caused by changes in the dietary pattern resulting from the market economy principles setting in after the 1989 revolution, and by an increased attention of the population to their health in the new socioeconomic conditions. If the trend continues, one might expect a decrease in mortality from IHD. On the other hand, the rise in diastolic blood pressure may be due to deteriorated control of hypertension.