This is a phase-II clinical study to assess whether intense passive mobilization of the elbow during the early stage is effective in preventing spasticity from occurring at a later stage. A group of subacute stroke patients was treated with the device named NEUROExos Elbow Module (NEEM) on a daily basis, in addition to traditional physical therapy. The outcome was assessed in terms of (i) system safety, (ii) system usability and (iii) treatment efficacy.