Elevations in C-reactive protein (CRP) concentration are associated with an increased risk of future coronary events in prospective studies and it has been suggested that CRP could be used to aid risk prediction. A +1444C>T polymorphism in the CRP gene has been associated with differences in CRP concentration. We investigated the effect of this polymorphism on the CRP response to periodontal therapy, an intermediate inflammatory stimulus. Clinical parameters, CRP, and interleukin-6 (IL-6) concentrations were evaluated in 55 consecutive patients suffering from periodontitis at baseline, 1, 7 and 30 days after an intensive course of periodontal treatment. In a multivariate analysis individuals homozygous for the +1444T allele showed higher CRP concentrations (day 1, 21.10+/-4.81 mg/L and day 7, 4.89+/-0.74 mg/L) compared with C-allele carriers (day 1, 12.37+/-1.61 mg/L and day 7, 3.08+/-2.00 mg/L). This effect was independent of conventional cardiovascular risk factors and inflammatory factors known to affect CRP concentrations. CRP genotype may need to be considered when CRP values are used in coronary risk prediction.