Association of gynaecomastia with hyperthyroidism is uncommon but has been well documented in the past. Gynaecomastia in a patient with hyperthyroidism rarely presents as a primary complaint. When this occurs, it may present a diagnostic challenge to the clinician. We present the case of a patient who was referred initially to the breast clinic with bilateral gynaecomastia. Hyperthyroidism was subsequently confirmed and treated; gynaecomastia regressed with return to the euthyroid state.