To describe clinical, radiographic, and morphologic findings in patients with IgG4-positive cells present on orbital biopsy specimens. Retrospective review (from January 1, 1993, through December 31, 2006) of patients with orbital biopsy specimens that excluded lymphoma; comparison of patients with and without IgG4-positive cells on immunostaining. Of 21 patients, 11 had increased IgG4-positive cells (defined as >10 cells on biopsy). Symptoms included eyelid or periocular swelling (8 patients) or proptosis (3 patients), with bilateral involvement in 6 patients. Computed tomographic imaging displayed lacrimal gland mass in 10 patients; 6 patients had lesions in other organs. Two patients had increased serum IgG4 levels. In 10 patients without IgG4-positive cells (≤10 cells on biopsy), 6 had proptosis, 1 had eyelid swelling, 2 had eyelid mass, and 1 had diplopia, all unilateral. None had systemic symptoms. Patients with IgG4-positive cells had longer symptom duration, and their biopsy specimens showed more background fibrosis, lymphoid hyperplasia, plasma cells, and eosinophils. The clinical appearance, high incidence of bilateral disease, association with lesions in other organs, and increased IgG4 serum levels in some patients-with an increased number of IgG4-positive cells in the biopsy specimen, which shows more background fibrosis, lymphoid hyperplasia, plasma cells, and eosinophils-indicate that these patients have an orbital manifestation of IgG4-associated systemic disease.