©2017 Wiley Periodicals, Inc. The metabolic syndrome is associated with higher ambulatory blood pressure. The authors studied the association of metabolic syndrome and masked hypertension (MHT) among African Americans with clinic-measured systolic/diastolic blood pressure (SBP/DBP) <140/90 mm Hg in the Jackson Heart Study. MHT was defined as daytime, nighttime, or 24-hour hypertension on ambulatory blood pressure monitoring. Among 359 participants not taking antihypertensive medication, the metabolic syndrome was associated with MHT (prevalence ratio, 1.38; 95% confidence interval, 1.10–1.74]). When metabolic syndrome components (clinic SBP/DBP 130–139/85–89 mm Hg, abdominal obesity, impaired glucose, low high-density lipoprotein cholesterol, high triglycerides) were analyzed separately, only clinic SBP/DBP 130–139/85–89 mm Hg was associated with MHT (prevalence ratio, 1.90; 95% confidence interval, 1.56–2.32]). The metabolic syndrome was not associated with MHT among participants not taking antihypertensive medication with SBP/DBP 130–139/85–89 and <130/85 mm Hg, separately, or among participants taking antihypertensive medication (n=393). Ambulatory blood pressure monitoring screening for MHT among African Americans should be considered based on clinic BP, not metabolic syndrome.