Hypertension is a leading cause of morbidity and mortality with surveillance often based on self-reported data. A systematic review and meta-analysis was completed to determine what empirical evidence exists regarding the agreement between measured and self-reported estimates of hypertension. Four electronic databases were searched to identify observational and experimental studies on adult populations. Searching identified 144 studies that examined the relationship between self-reported and directly-measured hypertension. Studies demonstrate that the prevalence of hypertension based on self-report is underestimated and that awareness levels are low and highly variable, ranging from 0 to 97%. Meta-analysis generated overall awareness estimates of 58% at the 140/90 mmHg cut-off and 62% at the 160/95 mmHg cut-off. Awareness levels were consistently higher for females. In many of the reviewed studies, standard guidelines for blood pressure measurement were not being followed or reporting of guideline compliance was poor. Lack of awareness is an important public health issue, yet this review demonstrates that the current practice of surveillance based on awareness alone is insufficient. These data indicate the importance of directly measuring blood pressure according to standardized protocols wherever possible, and increasing population awareness both to increase the validity of self-report and to ensure early diagnosis and treatment.