Coronary artery disease (CAD) plaque rupture leads to occlusive thrombosis, causing acute myocardial infarction requiring immediate life-saving treatment. The blood clot is supported by a mesh of fibrin fibres that are generated through the polymerisation of fibrin. We recently showed that fibrin also produces a film on the surface of blood clots. Our aim was to study if fibrin film occurs intravascularly on thrombi from patients with myocardial infarction. In this observational study, we recruited 42 patients with acute ST-elevation myocardial infarction (STEMI) and obtained intra-coronary thrombi using catheter-guided aspiration thrombectomy. We used a protocol that avoids air contact and immediately fixes the sample upon thrombectomy. Thrombi were analysed by tiled scanning electron micrographs to analyse percentage coverage by fibrin film. We found that all thrombi showed surface areas covered with fibrin film. Some film coverage was discontinuous. Total film coverage was on average 24.1±17.0% (range of 4.6-77.2%). Percentage of film coverage was positively correlated with the time from onset of symptoms to thrombectomy (ischaemia duration), and negatively with in-vitro clot formation time. Discontinuous film did not correlate with plasmin generation. These findings show that fibrin film is an integral structural feature that covers around one quarter of the surface of all coronary thrombi, and that older thrombi contain more film. This new structure on thrombi may have important implications for clot contraction, resistance to thrombolysis, and mechanical clot extraction.