Due to intracardiac circulatory changes atrial fibrillation creates conditions for thrombus formation in the left atrial appendage (LAA). The presence of thrombus in LAA is poor prognostic factor of subsequent cardiovascular events. It is the source of up to 64% of ischemic stroke cases, and concomitant anticoagulant therapy leads to a high frequency of hemorrhagic conversion. For patient with symptomatic and drug-refractory arrhythmia is recommended surgical rhythm correction or electrical cardioversion. There is a high risk of cardioembolic stroke during the intervention, so it is necessary to exclude LAA thrombosis at pre-operation stage. The main method of LAA visualization is transesophageal echocardiography, but today computed tomography and, less, magnetic resonance tomography become important. The purpose of this review is to analyze the possibilities of each visualisation technique and their role in the diagnostic algorithm when examining patients before catheter ablation of atrial fibrillation sources.