Background: Platelets play a pivotal role in the pathogenesis of acute coronary syndrome (ACS) and acute or chronic complications following percutaneous coronary intervention (PCI) as well. Platelet inhibition is a cornerstone treatment in the management of these patients. Thrombocytopenia in patients with ACS is uncommon. Idiopathic thrombocytopenic purpura (ITP) is a rare phenomenon; nevertheless, some case series presenting concomitant ACS and ITP have been described in the literature. The safety of antiplatelet therapy and PCI in patients who have ACS and thrombocytopenia is limited. Case summary: We present a case of a 60-year-old patient with ITP who was admitted with unstable angina pectoris. On admission, the platelet count was 23 Å~ 109/L. Coronary CT angiography revealed severe stenosis in the mid portion of RCA. After one-week treatment with high-dose Prednisolone, the platelet count recovered, and coronary catheterization was performed. Successful PCI to the RCA with drug-eluting stent was performed. The patient was discharged on dual antiplatelet therapy. Conclusion: The case suggests that PCI is a suitable treatment for ITP patients with ACS. Hemostasis is the major concern in managing these patients. The treatment strategy may be based on platelet function rather than platelet count alone. Further analysis of antiplatelet therapies as mono or dual therapy are needed.