Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. Our previous primary health surveys in 2013 and 2018 show that 25.8% to 34.1% of adults have raised BP, which is associated with cardiovascular, cerebrovascular, and renovascular morbidity and mortality. 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. An opportunistic cross-sectional survey of volunteers aged ≥18 was carried out in May 2017. Blood pressure measurement, the definition of hypertension and statistical analysis followed the standard MMM protocol. We recruited 292 sites in all 34 provinces in Indonesia, and screened in public areas and offices as well as health centres. A total of 69 307 individuals were screened. After multiple imputation, 23 892 (34.5%) had hypertension. Of individuals not receiving antihypertensive medication, 20.0% were hypertensive. Among individuals receiving antihypertensive medication, 7885 (62.8%) had uncontrolled BP. MMM17 was the largest standardized screening campaign for BP measurement in our country. The proportion of individuals identified with hypertension and the percentage of those with uncontrolled BP on medication provide evidence of the substantial challenges in managing hypertension in the community. These results suggest that opportunistic screening can identify significant numbers of individuals with raised BP.