Although no treatment guidelines exist, C1 esterase inhibitor concentrate (C1-INH) is used on an off label basis for management of ACEI acquired angioedema (ACEI AAE).<h4>Objective</h4>To evaluate the efficacy of C1-INH in management of ACEI AAE at our local centers.<h4>Results</h4>Nine patients, from 3 academic sites, were identified through Allergy Service consultation data and records from Diagnostic Services Manitoba, Canada from 2010-2020. The gene discussed is C1S; the disease is acquired angioedema.