Summary Aim To examine the prevalence of hypertension and the rates of hypertension awareness by investigating treatment and control among respondents to the EURODIAB IDDM Complications Study, and to explore the variation in hypertension management by age, sex and end‐organ damage. Methods A cross‐sectional study, examining 3250 randomly selected Type 1 diabetic patients from 31 diabetes clinics in 16 European countries between 1989 and 1990. Mean age was 32.7 years ( sd = 10.0) and mean duration of diabetes mellitus (DM) was 14.7 years ( sd = 9.3). Subjects were asked about a history of high blood pressure (BP) and current prescribed medications were recorded by the subject’s physician. Hypertension was defined as having a systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg or current use of antihypertensives. Control was defined as a BP < 130/85 mmHg. Results Twenty‐four per cent of subjects had hypertension, among whom fewer than one‐half (48.5%) were aware of a previous diagnosis and a similar proportion (42.2%) were on treatment. Only 11.3% of those with hypertension were both treated and controlled. The majority (81%) of those receiving drug therapy for hypertension were on a single drug, most commonly an angiotensin‐converting enzyme inhibitor (47%). Conclusion These data show the extent of undermanagement of hypertension in Type 1 DM across Europe prior to the publication of the St. Vincent Declaration and provide a useful baseline against which future improvements in the management of hypertension can be monitored. Diabet. Med. 16, 41–49 (1999)