Virus-specific T-cell (VST) infusion becomes a promising alternative treatment for refractory viral infections after hematopoietic stem cell transplantation (HSCT). However, VSTs are often infused during an immunosuppressive treatment course, especially corticosteroids, which are a first-line curative treatment of graft-versus-host disease (GVHD). We were interested in whether corticosteroids could affect adenovirus (ADV)-VST functions. After interferon (IFN)-γ based immunomagnetic selection, ADV-VSTs were in vitro expanded according to three different culture conditions: without methylprednisolone (MP; n = 7), with a final concentration of MP 1 µg/mL (n = 7) or MP 2 µg/mL (n = 7) during 28 ± 11 days. Efficacy and alloreactivity of expanded ADV-VSTs was controlled in vitro. MP transitorily inhibited ADV-VST early expansion. No impairment of specific IFN-γ secretion capacity and cytotoxicity of ADV-VSTs was observed in the presence of MP. However, specific proliferation and alloreactivity of ADV-VSTs were decreased in the presence of MP. Altogether, these results and the preliminary encouraging clinical experiences of co-administration of MP 1 mg/kg and ADV-VSTs will contribute to safe and efficient use of anti-viral immunotherapy.