Heavy Chain Deposition Disease is a rare Monoclonal Immunoglobulin Deposition Disease presenting with proteinuria, hypertension and renal failure. Pathogenesis involves clonal expansion of B cells secreting free Ig heavy chains that deposit in the kidney. Diagnosis requires renal biopsy, where immunofluorescence detection of monoclonal heavy chains in the absence of light chains is pathognomonic. Treatment aims to suppress B cell production of the free heavy chains or eliminate abnormal B cell clone. We report an unusual case of HCDD with acquired angioedema, and postulate that free heavy chains may block C1 esterase inhibitor function, predisposing to bradykinin mediated angioedema.