Background: Reslizumab is an anti-interleukin 5 monoclonal antibody that has demonstrated to reduce the risk of severe exacerbations and to improve symptoms, lung function, and quality of life in randomized controlled trials that included patients with severe eosinophilic uncontrolled asthma (SEUA) and a history of severe exacerbations., Objective: The aim of the present study was to evaluate the effectiveness of add-on reslizumab in a cohort of patients with SEUA under real-life conditions., Methods: This was a multi-centre, retrospective, real-life study that included subjects with SEUA treated with reslizumab in 44 asthma units throughout Spain. Eligible patients were those who had received at least one dose of reslizumab as part of normal clinical practice. The primary endpoint was complete asthma control at 52 weeks, defined as absence of severe exacerbations, ACT ≥20 and no maintenance oral corticosteroids (OCS). Demographic, clinical, and functional data were collected at baseline (T0), after four to six months (T1); after 12 months (T2) and beyond 12 months of therapy (T3)., Results: Treatment with reslizumab achieved complete asthma control in 40% of the 208 included SEUA patients and led to a significant reduction in exacerbations (from 3.0; IQR: 2.0-4.0 at V0 to 0.0; IQR: 0.0-0.0 at V2), maintenance OCS use (from 54.8% (95% CI: 48.0-61.6 at T0 to 18.5% (95% CI: 12.5-24.5 at T2) and a meaningful improvement in symptoms in the entire treated population: ACT increased from 12.8 ± 4.5 at V0 to 20.0 ± 5.1 at V2 (p < 0.001). Most of the improvement achieved at 12 months was obtained at 4-6 months. The retention (continuation) rate of reslizumab was 75% through 2 years (95CI%: 1.9-2.1). Overall, reslizumab showed an adequate safety profile., Conclusion: Reslizumab is an effective therapy for SEUA with adequate safety profile in real-life conditions., Competing Interests: Luis A Pérez de Llano declares to have received grants and/or fees for consultancy or speeches from Novartis, Astra-Zeneca, GSK, Teva, Boehringer-Ingelheim, Chiesi, Sanofi, MSD, FAES, Techdow Pharma, Leo Pharma, Gebro, Gilead, Menarini, Mundipharma, and Esteve. Borja G Cosío declares he has received speaking or advisory fees, or economic aid to attend congresses from Astra-Zeneca, GSK, Novartis, Chiesi, Mundipharma, Menarini, Sanofi, TEVA, Boehringer-Ingelheim, and Rovi. Ignacio Lobato Astiárraga declares he has received speaker fees, consulting fees from Astra-Zeneca, GlaxoSmithKline, Novartis, Chiesi, Sanofi, Boehringer, SEPAR, and Teva. Gregorio Soto Campos declares he has received speaker fees, consulting fees from ALK, Astra-Zeneca, Bial, Boehringer-Ingelheim, Chiesi, GlaxoSmithKline, Novartis, Sanofi, and Teva. Miguel Ángel Tejedor Alonso declares that there is no relevant conflict of interest. Nuria Marina Malanda declares she has received speaker fees, consulting fees from Astra-Zeneca, Sanofi, GlaxoSmithKline, Chiesi, Pfizer, Novartis, and Teva. Alicia Padilla Galo declares she has received speaking or advisory fees, or economic aid to attend congresses from Novartis, Teva, Astra-Zeneca, GlaxoSmithKline, and ALK. Isabel Urrutia Landa declares she has received speaking or advisory fees, or economic aid to attend congresses from Astra-Zeneca, Sanofi, GlaxoSmithKline, Chiesi, Bial Aristegui, Teva, Novartis, ALK, Boehringer-Ingelheim, and Mundi Pharma. Francisco Javier Michel de la Rosa has received speaker fees and/or consulting fees and/or support attend Congresses from the following: Astra-Zeneca, Boehringer-Ingelheim, Chiesi, CSL Behring, GlaxoSmithKline, Grifols, Menarini, Novartis, Sanofi Aventis, and Teva. Ismael García-Moguel declares he has received speaking or advisory fees, or economic aid to attend congresses from Astra-Zeneca, Sanofi, GlaxoSmithKline, Chiesi, Mundipharma, Allergy therapeutics, Novartis, Stallergenes Greer, and Teva. The authors report no other conflicts of interest in this work., (© 2022 Pérez de Llano et al.)