Heparin is an anticoagulant which has been widely used in various clinical settings, from thromboprophylaxis to the treatment of thromboembolism. Heparin-induced thrombocytopenia (HIT) is a rare medical condition with severe complications if unrecognised, and it carries significant risks of co-morbidities and mortality. The incidence of HIT is relatively less common in low molecular weight heparin. HIT is more common in the venous system than the arterial circulatory system, and it is rare to see multi-vessel coronary artery thrombosis due to HIT. We hereby report a case of multi-vessel coronary thrombosis secondary to low molecular weight HIT, presenting as a case of ST-segment elevation myocardial infarction. We learned from the case that low molecular weight heparin can cause thrombosis secondary to HIT and HIT could be one of the differential diagnoses in those presenting with ST-elevation myocardial infarct and recent exposure to low molecular weight heparin.