Little data is available on the bleeding risk and outcomes of cancer patients with chronic thrombocytopenia who underwent cardiac catheterization. We sought to assess the safety of coronary angiography, percutaneous coronary intervention, and antiplatelet therapy in cancer patients with acute coronary syndrome (ACS) and chronic thrombocytopenia. We performed a retrospective study of patients with chronic thrombocytopenia who underwent cardiac catheterization for ACS between November 2009 and November 2015. Preprocedural platelet counts were classified into 3 groups: mild thrombocytopenia (50,000 to 100,000/µL), moderate thrombocytopenia (30,000 to 50,000/µL), and severe thrombocytopenia (<30,000/µL). Postprocedural bleeding complications and overall survival (OS) were recorded. A total of 98 patients were included. Mean platelet count on admission was 47.63 ± 29.85 K/µL. Severe thrombocytopenia was identified in 36 patients (36.7%), moderate thrombocytopenia in 20 patients (20.4%), and mild thrombocytopenia in 42 patients (42.9%). Aspirin therapy (alone or in combination with clopidogrel) was used in 66 patients (67.3%), whereas 27 patients (27.6%) were on dual antiplatelet therapy. One procedure-related retroperitoneal hematoma and 3 procedure-related small hematomas were identified. No cerebrovascular events related to the procedure or the antiplatelet therapy were noted. Moderate thrombocytopenia was associated with decreased OS, whereas aspirin, dual antiplatelet therapy, and statin use showed a trend of improved OS. In conclusion, we suggest that coronary angiography and percutaneous coronary intervention can be performed safely in cancer patients with chronic thrombocytopenia. Aspirin therapy and dual antiplatelet therapy should be considered in cancer patients with chronic thrombocytopenia and ACS.