Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. May Measurement Month (MMM) is a global initiative aimed at raising awareness of high BP and to act as a temporary solution to the lack of screening programmes worldwide. National Health Surveys, PURE and CESCAS Chilean cohorts have shown a high prevalence of hypertension, with a significant proportion of people unaware of being hypertensive or under treatment but with uncontrolled BP. An opportunistic cross-sectional survey of volunteers aged ≥18 was carried out in May 2017. BP measurement, the definition of hypertension and statistical analysis followed the MMM protocol. Sixty-seven sites participated. Most screening sites were National Heath Public System outpatient clinics, mainly in the 9th region of the country. In addition, clinical research sites and private clinics participated. Overall, 4754 individuals were screened during MMM17. After multiple imputations, 1153 (24.2%) had hypertension. Of individuals not receiving anti-hypertensive medication, 653 (15.3%) were hypertensive. Of the 500 individuals receiving anti-hypertensive medication, 162 (32.5%) had uncontrolled BP. MMM17 was one of the largest BP screening campaigns performed in Chile. It demonstrated a high proportion of hypertension among screenees with a low proportion the individuals with controlled hypertension in the community. The high percentage of persons untreated or with uncontrolled hypertension whilst on pharmacologic treatment suggests that systematic screening programmes may be a useful tool to improve hypertension control in Chile.