Background Tumor necrosis factor-α is a key mediator in the pathogenesis of psoriasis.Infliximab is a monoclonal antibody that specifically binds to tumor necrosis factor-a.The purpose of this study was to validate the efficacy and safety of 5 mg/kg infiiximab therapy in Chinese patients with moderate to severe plaque psoriasis.Methods In this multicenter,double-blind,placebo-controlled trial,129 patients with moderate-to-severe psoriasis were randomized to the induction therapy (weeks 0,2 and 6) with infliximab 5 mg/kg (n=84) or placebo (n=45),followed with infliximab 5 mg/kg scheduled at week 14 and week 22 in the infliximab group,and infliximab 5 mg/kg scheduled at weeks 10,12 and 16 in the placebo group,The primary end point was the proportion of patients who achieved at least 75％improvement in Psoriasis Area and Severity Index (PASI 75 response rate) from baseline at week 10.Results At week 10,B1.0％ of patients treated with infliximab (5 mg/kg) achieved a 75％ or greater improvement compared with 2.2％ of patients treated with placebo (P ＜0.001).A significant improvement in PASI,Physician's Global Assessment (PGA) and Dermatology Life Quality Index (DLQI),was seen from week 6 through week 14 in the infliximab group compared with the placebo group.Through week 22,PASI,PGA,DLQI were well maintained.The incidence of adverse events for the infliximab treatment group was slightly higher in comparison to the placebo treatment group during the first 10 weeks without statistical significance.However,there were 3 cases of tuberculosis that developed during the 26 weeks treatment with infliximal.Conclusions Infliximab treatment was effective as induction and maintenance treatments for Chinese patients with moderate to severe plaque psoriasis.Most drug-induced adverse events were mild to moderate,and well tolerated.Screening for tuberculosis is essential and prophylactic treatment should be given if necessary.