Alefacept is a fully human fusion protein for use in adult patients with moderate to severe chronic plaque psoriasis. Its dual mechanism of action involves inhibition of T-cell activation and selective reduction of memory T cells. We report the clinical course of two patients with hepatitis C virus (HCV) infection who have received alefacept for psoriasis. Consistent with its mechanism of action, administration of alefacept led to transient decreases in CD4+ and CD8+ T-cell counts. However, these reductions were not associated with an increase in HCV viral load or exacerbation of infection. Liver enzymes remained stable throughout the treatment and follow-up periods. Alefacept has a selective mechanism of action that specifically targets memory T cells and this selectivity may account for its safety and tolerability in patients with hepatitis.