C-reactive protein (CRP) is a marker of systemic inflammation and cardiovascular disease. CRP has been recommended as an adjunct screening tool to stratify cardiovascular risk in the general population. Evidence regarding within-person variability of CRP in the general population is limited. Short-term variability in CRP has important implications for its use & interpretation in clinical practice and research studies. This study found significant short-term (approximately 2.5 weeks) within-person variability in CRP levels, particularly at high values. Approximately one-third of persons with elevated CRP levels were reclassified as having normal CRP levels after repeated testing. Our results are consistent with those of previous studies conducted in small selected populations (eg, patients with ischemic heart disease) or in which measurements were months or years apart.