BACKGROUND & AIMS: Treatments for Crohn's disease (CD) have been linked to serious infections, malignancies, and dermatologic complications. We pooled and analyzed clinical trials of certolizumab pegol, a pegylated humanized Fab' fragment against tumor necrosis factor, to quantify safety events in patients with CD. METHODS: We collected data from 5 placebo-controlled trials, 9 open-label studies, and 1 dose-regimen study, conducted globally through April 2014. A total of 2570 patients with moderate to severe CD were treated with certolizumab pegol, with 4378.1 patient-years of exposure. Data were analyzed in 2 groups: patients from placebo-controlled (PC) trials treated with placebo (n = 875) or certolizumab pegol (n = 919) for 6 to 38 weeks (the PC group) or all patients exposed to certolizumab pegol (n = 2570), for durations of 6 to 362 weeks (the all-studies group). Incidence rates (IRs; incidence/100 patient-years) of adverse events (AEs) were calculated from first dose through 70 days (approximately 5 half-lives) after the last dose. RESULTS: In the PC group, IRs for serious AEs were similar among patients given certolizumab pegol (31.35/100 patient-years) vs placebo (24.33/100 patient-years). IRs of serious infections or malignancies were low among patients receiving short-term treatment with certolizumab pegol (8.49/100 patient-years and 1.01/100 patient-years, respectively, in the PC group) and did not increase with long-term treatment (6.47/100 patient-years and 0.80/100 patient-years, respectively, in the all-studies group). IRs of psoriasis or psoriasiform dermatitis were low in the PC group (1.01/100 patient-years and 0/100 patient-years, respectively); in the placebo group, these IRs were 0.38 per 100 patient-years and 0 per 100 patient-years, respectively. IRs of psoriasis or psoriasiform dermatitis did not increase with long-term treatment (0.93/100 patient-years and 0.09/100 patient-years, respectively, in the all-studies group). CONCLUSIONS: Based on an analysis of data pooled from 15 trials of patients with CD, the safety profile for long-term therapy with certolizumab pegol therapy is similar to that reported from short-term studies. Overall rates of AEs, serious infections, malignancies, and psoriasis did not increase with long-term treatment, suggesting a favorable risk-benefit ratio with long-term certolizumab pegol therapy in CD.