Pentraxin 3 is an acute phase marker that belongs to the same protein family as C-reactive protein (CRP). The aim of this study was to compare the acute phase reactions of pentraxin 3 and CRP in humans. High sensitivity CRP and pentraxin 3 were analyzed in blood samples from orthopedic surgery (n = 29) and coronary bypass patients (n = 21). The samples were collected prior to surgery and 4 and 30 days after surgery, respectively. Both CRP and pentraxin 3 were significantly increased at day 4. Median pentraxin 3 values increased from 4,021 to 7,459 pg/mL in the orthopedic group and from 4,637 pg/mL to 10,419 pg/mL in the coronary bypass group while CRP increased from 6.3 mg/L to 151.6 mg/L and from 5.7 mg/L to 176.3 mg/L in the same groups. Pentraxin 3 shows a much smaller increment in humans in comparison with CRP.