Traffice Noise and Hypertension. First communication: the question whether traffic noise could be a risk factor of essential hypertension was studied by means of interviews. In Bonn 931 inhabitants between 20 and 59 years of age, who lived either in streets with high (minimum: 9062 cars/day) or low (maximum: 1182 cars/day) traffic volumes were interviewed. While no differences were found in the frequencies of treatment of diabetes mellitus, gout, asthma and peptic ulcer, there was a difference in response to treatment of hypertension (p = 0.002); in the noisy area 22.8% and in the quiet area 14.6% of respondents stated that they were treated. Also in both male and females aged 29-39 years, there was a connection between hypertensive treatment and the duration of stay in the noisy area (p less than 0.05).