Alefacept belongs to the new generation of drugs applied in the treatment of psoriasis. It is an immunomodulatory recombinant, fully human lymphocyte function associated antigen-3/immunoglobulin G1 fusion protein (LFA-3-Ig) CD2 antagonist that targets memory-effector T cells by binding CD2 on the T cell surface. It blocks the interactions of leukocyte functional antigen (LFA)-3 with CD2 interaction. This drug is used to treat moderate-to-severe chronic plaque psoriasis and there was conducted a pilot study of psoriatic arthritis. It was observed that Alefacept had reduced peripheral-blood memory effector T-lymphocyte (CD45RO+) counts, cells which are responsible for sustaining the disease. Pharyngitis, dizziness, increased cough, nausea, pruritus, myalgia, chills, injection site inflammation, and accidental injury were recorded. So far, in the conducted trials no generalised immunosuppression or increased risk of infection or malignancy were observed. The possibility of increased risk of infections and malignancies must be considered because of reduced lymphocyte counts.