Objective:To evaluate the association of cognitive function,clinical symptoms,and plasma C-reac-tive protein(CRP)level in patients with treatment-resistant obsessive-compulsive disorder(trOCD).Methods:Fif-ty-five patients with trOCD,45 patients with non-trOCD,and 65 normal controls were enrolled.The Yale-Brown Obsessive-Compulsive Scale(YBOCS),Hamilton depression scale,Hamilton anxiety scale,MATRICS Consensus Cognitive Battery(MCCB)were used to evaluate the OCD,depressive or anxious clinical symptoms,as well as cognitive function,in above-mentioned subjects.The plasma CRP level were examined by using the latex-enhanced immunoturbidimetry methods in three groups.Results:Compared with the other two groups,the MCCB cognition scores,especially information processing speed,working memory,inferential knowledge and problem-solving skills were higher in the trOCD group,respectively(Ps＜0.05).The plasma CRP level and percentage of cases with high CRP level(≥3 mg/L)in the trCOD group were higher than those in other two groups(P＜0.05).However,difference of MCCB and its factorial scores revealed no statistical significances in non-trOCD group(Ps＞0.05).Logistic regression analysis showed that potential risk factors of treatment-resistant OCD including,more obsessive-compulsive symptoms(OR=2.01),higher severity of OCD(OR=2.29),lower MCCB total scores(OR=4.01),higher plasma CRP level(OR=4.24),and longer disease course of OCD(OR=3.23)(P＜0.05).Conclusion:Impaired cognitive function,high plasma C-reactive protein level,may be associated with more obsessive-compul-sive symptoms,higher severity of OCD,as well as long disease course of OCD.