The Munich Blood Pressure Study I (MBS 1980/81) was designed to answer questions relating to prevalence, awareness, treatment, and control of hypertension in Munich. From the target population of Munich residents, 30 to 69 years of age and German nationality, a random sample of 34000 subjects was drawn. A response rate of about 70% was achieved. The prevalence of hypertension (≥ 160 mmHg systolic and/or ≥ 95 mmHg diastolic) in the study population is 14%. It shows a high correlation with age and sex. The prevalence in men (17.7%) is substantially higher than in women (10.7%). In both sexes the frequency of high blood pressure increases with age. Women prove to be more aware of their hypertensive status and have a higher proportion of cases under treatment and control. The results of the MBS I demonstrate the importance of a blood pressure program for the Munich population.