Background and Purpose: Orbital and cranial form of idiopathic inflammatory pseudotumors (IIPs) are rare disorders with heterogeneous clinical presentations. Corticosteroids have been the first-line treatment for IIPs, but they are not always effective. Methods: We reviewed the medical records of three patients with orbital or cranial form of IIP who were treated with tacrolimus as an adjuvant treatment. Results: The three patients showed favorable outcomes with the addition of tacrolimus, which is a calcineurin inhibitor that inhibits T-cell activation and T-cell-dependent B-cell activation. Conclusions: Tacrolimus may be a safe and effective immunosuppressant for refractory or relapsing form of orbital or cranial IIPs.