Background: The impact of the encounter between coronary heart disease (CHD) and cancer, and in particular hematologic malignancies (HM), remains poorly understood. Objective: The aim of this analysis was to clarify how HM affects the prognosis of acute coronary syndrome (ACS). We analyzed German health insurance data from 11 regional Ortskrankenkassen (AOK) of patients hospitalized for ACS between January 2010 and December 2018, matched by age, sex and all comorbidities for short- and long-term survival and major adverse cardiac events (MACE). Results: Of 439,716 patients with ACS, 2104 (0.5%) also had an HM. Myelodysplastic/myeloproliferative disorders (27.7%), lymphocytic leukemias (24.8%), and multiple myeloma (22.4%) predominated. These patients were about 6 years older (78 vs. 72 years *). They had an ST-segment elevation myocardial infarction (STEMI, 18.2 vs. 34.9% *) less often and more often had a non-STEMI (NSTEMI, 81.8 vs. 65.1% *). With the exception of dyslipidemia, these patients had more concomitant and previous cardiovascular disease and a worse NYHA stage. They were less likely to undergo coronary angiography (65.3 vs. 71.6% *) and percutaneous coronary intervention (PCI, 44.3 vs. 52.0% *), although the number of bleeding events was not relevantly increased (p = 0.22). After adjustment for the patients’ risk profile, the HM was associated with reduced long-term survival. However, this was not true for short-term survival. Here, there was no difference in the STEMI patients, * p < 0.001. Conclusion: Survival in ACS and HM is significantly lower, possibly due to the avoidance of PCI because of a perceived increased risk of bleeding.