Background: Granulocyte and monocyte adsorptive apheresis (GMA) with Adacolumn has been widely used as a remission induction therapy for patients with active ulcerative colitis (UC). However, an appropriate GMA treatment strategy related to concomitant medication in patients with active UC has not been established. Herein, we investigated the in uence of concomitant medications in the remission induction of GMA in patients with active UC.Methods: This multicenter retrospective cohort study included patients with UC who underwent GMA in ve independent institutions in Japan from January 2011 to July 2021. Clinical factors associated with clinical remission (CR) were analyzed statistically.Result: A total of 133 patients with active UC who underwent GMA were included. Seventy-four patients achieved a CR after GMA. The overall CR rate was 55.6%. The multivariable analysis revealed that concomitant medication with 5aminosalicylic acid, Mayo endoscopic subscore (MES), and concomitant medication with immunosuppressors (IMs) remained as predictors of CR after GMA (p = 0.027, odds ratio [OR] 0.157; p = 0.017, OR 2.983; and p = 0.008, OR 3.361, respectively). In the subgroup analysis in patients with MES 2, concomitant medication with IMs was demonstrated as a signi cant negative factor of CR after GMA (p = 0.042, OR 2.823). Seventy-four patients who achieved CR after GMA were followed up for 52 weeks. CR was sustained in 24 of 74 patients (32%), and the median remission time was 30 weeks. In the multivariable analysis, the maintenance therapy with IMs was demonstrated as a signi cant positive factor of sustained CR up to 52 weeks (p = 0.038, OR 2.214). The rate of sustained CR in patients with 5-ASA and IMs was not different when compared with that in patients with 5-ASA only (p = 0.248). On the other hands, the rate of sustained CR in patients with biologics and IMs was signi cantly higher than that in patients with biologics only (p = 0.002).Conclusion: GMA was more effective for patients with active UC that relapsed under treatment without IM. Furthermore, the addition of IMs should be considered in patients on maintenance therapy with biologics after GMA.