Hiatus hernia is a common medical condition. An elderly woman being investigated for dyspnoea of unknown aetiology had a transthoracic echocardiogram as part of her investigations. This alarmingly demonstrated a large left atrial mass. Further assessment with cardiac magnetic resonance imaging revealed a large hiatus hernia compressing the left atrium and no intra-cardiac mass. The case succinctly highlights gastrointestinal pathology simulating cardiac symptoms and masses.