BACKGROUND: Laboratory tests are routinely ordered to identify or rule out a cause in patients with chronic urticaria/angioedema (CUA). The results of these tests are usually within normal limits or unremarkable. OBJECTIVE: To investigate the proportion of abnormal test results in patients with CUA leading to a change in management and in outcomes of care. METHODS: Retrospective analysis of a random sample of adult patients with CUA from 2001-2009. RESULTS: Cases totaled 356: 166 with urticaria and angioedema (AE), 187 with urticaria, and 3 with only AE. Patients were predominately women (69.1%) and white (75.6%), with a mean age of 48 ± 15 years. Abnormalities were commonly seen in complete blood counts (34%) and in complete metabolic panels (9.4%). Among the 1,872 tests that were ordered, results of 319 (17%) were abnormal. Of 356 patients, 30 underwent further testing because of abnormalities in laboratory work. This represented 30 of 1,872 tests (1.60%). Only 1 patient benefited from a subsequent change in management. CONCLUSIONS: Laboratory testing in CUA patients referred for an Allergy and Immunology evaluation rarely lead to changes in management resulting in improved outcomes of care.