Fifty-five patients, suspected on clinical grounds of having an inflammatory orbital pseudotumor, were studied retrospectively. Clinical groups based on natural history or response to corticosteroid therapy were correlated with available histopathological findings. These findings were interpreted without knowledge of clinical grouping or previous pathology reports. Although dogmatic statements are not possible, several conclusions are warranted. (1) Bilaterality was not significantly related to response to steroids or development of systemic disease. (2) B-scan ultrasonography, while not diagnostic, provided a worthwhile investigative technique. (3) Germinal follicles are associated with a good prognosis and indicate a reactive lesion, while diffusely distributed lymphoblasts are associated with steroid unresponsiveness and a probable neoplastic lymphoid lesions. (4) Eosinophils are more common in reactive lesions than in presumed lymphomas. Other cellular components showed no preferential distribution in either neoplastic or nonneoplastic groups.