Determination of C-reactive protein (CRP) and high-sensitivity CRP (hs-CRP), markers of systemic inflammation and atherosclerosis risk, usually requires serum samples, while heparin plasma samples are routinely collected for routine chemistry. This study evaluates the use of heparin plasma samples for hs-CRP and CRP determinations using immunoturbidimetric methods on an Olympus system. As a result, analytical performance, including linearity, imprecision values, and determination from 185 clinical samples, are not affected by the type of sampling, validating the use of heparin plasma samples for CRP and hs-CRP determination with Olympus reagents.